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1.
The concentration and functionality of the -adrenoceptor (-AR) subtypes in the genital tract of cyclic heifers were investigated. In each tissue sample, a single class of 1-ARs was observed, whereas two distinct classes of 2-ARs were discriminated: low-affinity (LA) and high-affinity (HA) 2-ARs. Statistical analysis showed the presence of significantly (p < 0.05) higher concentrations of all -AR subtypes in the follicle than in the corpus luteum. No significant differences were found in the ovary or myometrium between the luteal and follicular phases. In the ovary, the density of 1-ARs was significantly (p < 0.05) higher than that of 2-ARs. By contrast, there were significantly (p < 0.05) more 2-ARs than 1-ARs in the myometrium. As far as 2-ARs are concerned, LA 2-ARs were significantly (p < 0.05) higher than HA 2-ARs in all tested tissues. Competition studies suggested that the rank order of potency of antagonists for 1-ARs was prazosin > phentolamine > yohimbine, whereas for 2-ARs the order of potency was yohimbine phentolamine > prazosin. Functional assays performed on myometrium showed that noradrenaline, phenylephrine and clonidine elicited concentration-dependent contractions only in dioestrus and pro-oestrus preparations and that clonidine was more effective than phenylephrine as a contractile agent. It appeared that there were no significant modifications in -AR affinity or concentration during the different stages of bovine oestrous cycle, whereas the uterine spontaneous activity and the responsiveness to -adrenergic stimulation was strongly influenced by hormonal levels. The modifications of uterine contractility observed during the oestrous cycle may be related to modifications induced in the transductional mechanisms of -ARs.  相似文献   

2.
The pharmacokinetics of enrofloxacin and its active metabolite ciprofloxacin were investigated in goats after a single intramuscular administration of enrofloxacin at 2.5 mg/kg body weight. The plasma concentrations of enrofloxacin and ciprofloxacin were determined simultaneously by a HPLC method. The peak concentrations (C max) of enrofloxacin (1.13 g/ml) and ciprofloxacin (0.24 g/ml) were observed at 0.8 and 1.2 h, respectively. The elimination half-life (t 1/2), volume of distribution (V d(area)), total body clearance (ClB) and mean residence time (MRT) of enrofloxacin were 0.74 h, 1.42 L/kg, 1329 ml/h per kg and 1.54 h, respectively. The t 1/2, area under the plasma concentration–time curve (AUC) and the MRT of ciprofloxacin were 1.38 h, 0.74 g h/ml and 2.73 h, respectively. The metabolic conversion of enrofloxacin to ciprofloxacin was appreciable (36%) and the sum of the plasma concentrations of enrofloxacin and ciprofloxacin was maintained at or above 0.1 g/ml for up to 4 h. Enrofloxacin appears to be useful for the treatment of goat diseases associated with pathogens sensitive to this drug.  相似文献   

3.
The pharmacokinetics of sulphadimidine after a single dose (200 mg/kg i.v.) was studied in five healthy lactating buffaloes. The study revealed that the drug attained its peak concentration of 314.0±13.0, 242.4±3.0 and 100.2±2.5 g/ml at 15 min, 30 min and 12 h in plasma, milk and uterine fluid, respectively. The pharmacokinetic parameters calculated by a 2-compartment open model gave values for t1, t1 and vdarea of 2.10±0.36 h, 12.36±0.57 h and 1.23±0.07 L/Kg, respectively. A high vdarea as well as a value of 0.74±0.08 for K12:K21- (tissue Plasma) indicates better penetration of the drug into the different body fluids and tissues, which is further supported by a high concentration obtained in milk and uterine fluid. The therapeutic concentration (50 g/ml) was maintained for around 24 h in plasma and milk and 12 h in uterine fluid. The results suggest that, apart from its use in systemic infections, the drug can be effectively used by the i.v. route in uterine and mammary gland infections. The dosages for maintaining concentration of 50 g/ml, 100 g/ml and 150 g/ml at convenient dosage intervals of 12 and 24 h were also determined.  相似文献   

4.
The purpose of the present investigation was to test the hypothesis that drug-induced changes in rumen contractions influence feed intake in dwarf goats. Intravenous (i.v.) administration of clonidine (1 g kg-1 min-1 for 10 min), xylazine (1 g kg-1 min-1 for 10 min), and PGF-2 (10 g kg-1 min-1 for 15 min) caused bradycardia and inhibition of rumen contractions. However, no appetite-stimulating effect of these drugs was observed. Other clinical changes induced by the 2-adrenergic agonists included slight sedation and a decrease in body temperature; all clinical effects of clonidine and xylazine were partly antagonized by tolazoline pretreatment (10 g kg-1 min-1 for 30 min). These results suggest that the CNS control of feeding differs in ruminants and monogastric species.In dwarf goats fasted for 2 h, i.v. administration of oxytocin (0.01 IU kg-1 min-1 for 15 min), vasopressin (0.01 IU kg-1 min-1 for 15 min), octapressin (0.003 IU kg-1 min-1 for 15 min) or PGE (0.8 g kg-1 min-1 for 15 min) did not change feeding behaviour during the two observation periods (0–30 min and 180–210 min after drug infusion, respectively). In previous studies, similar doses of these drugs induced changes in heart rate and inhibition of rumen contraction in goats. These findings demonstrate that drug-induced changes in forestomach contractions do not simply cause changes in feeding behaviour. The i.v. infusion of the PGF2 analogues etiproston (10 g kg-1 min-1 for 15 min), luprostiol (30 g kg-1 min-1 for 15 min), cloprostenol (1 g kg-1 min-1 for 15 min) and tiaprost (1 g kg-1 min-1 for 15 min) induced hypophagic effects and stimulated intestinal propulsion.  相似文献   

5.
With electromyography and strain gauges the uterine motility of the sow during the oestrous cycle and early pregnancy was studied. Special attention was paid to characterization of myometrial activity at the time of intrauterine migration of blastocysts.From recordings of 4 animals (3 became pregnant) 3 types of electrical spiking activity (each could be correlated with an elevation of the strain gauge tension) were discerned. Two of them appeared regularly and were suitable for analysis: High Voltage Slow Acticity (with relative high amplitude and low frequency of spikes) and Low Voltage Fast Activity (with relative low aplitude and high frequency of spikes).The sexual status markedly influenced myometrial activity: during prooestrus and oestrus only one type of electrical activity was present whereas the myoelectrical complex (an episode of this activity and the subsequent interval of inactivity) was shorter than 10 min. During dioestrus the myoelectrical complex was longer than 10 min and High Voltage Slow Activity (solely on the cervix and bifurcation) and Low Voltage Fast Activity occurred simultaneously in episodes which mainly appeared to originate on the bifurcation.The characteristics of uterine activity during pregnancy were similar to those of a cyclic sow until day 12. It was only on day 12 that gestation appeared from an increased frequency of myoelectrical complexes.It is concluded that Low Voltage Fast Activity as it was found on the uterine horn at days 8–9 might be involved in the process of intra-uterine migration of blastocysts. In cyclic and in pregnant animals the patterns of Low Voltage Fast Activity were similar. Therefore, the occurrence of Low Voltage Fast Activity is independent of the actual presence of blastocysts. It seems to be exhibited in dependence on the ovarian hormones.  相似文献   

6.
A pharmacokinetic study of doxycycline after intravenous administration at 5 mg/kg body weight in goats revealed that a concentration of 0.5 g/ml was maintained for 5 min-2 h, 4–12 h, 2–12 h and 5 min- >48 h in plasma, interstitial fluid, milk and urine respectively. The low t1/2 of 0.73±0.11 h and high t1/2 of 16.63±1.58 h show that the drug is rapidly distributed but slowly eliminated from the body. The tissue:plasma concentration of 4.86±1.06 during the elimination phase [K12/(K21-)] indicates a high expected tissue concentration, which is supported by similarly increased drug concentration in interstitial fluid and milk. The high Vdarea of 9.78±0.86 L/kg observed denotes that, apart from its wide distribution, the drug may be stored in fat depots as it is known to be highly lipophilic. As the drug maintained a therapeutic concentration for a shorter time in plasma, and the calculated dose rate for maintaining a minimal plasma concentration of 0.5–1.5 g/ml is relatively high, it may not be of much use in treating septicaemia in this species. Since the observed tissue:plasma concentration was higher and a therapeutic concentration was maintained in interstitial fluid and milk for longer, the drug can be used for other systemic infections at a lower dose rate than that required for treating septicaemia. As the drug maintained a very high concentration in urine, it may be of particular value in treating urinary tract infections caused by sensitive micro-organisms.  相似文献   

7.
The oxidative metabolism of aldicarb (ALD), a carbamate pesticide, and fenbendazole (FBZ), an anthelmintic, was studied using cultured hepatocytes obtained from 4 goats and a bullock and incubated with ALD (50 mol/L) and FBZ (10 mol/L). The parent compounds and the metabolites were measured by HPLC. Both compounds are metabolized at the sulphur atom via two sequential oxidations, first to the sulphoxide (aldicarb sulphoxide and oxfendazole, respectively) and then to the sulphone. Oxfendazole and fenbendazole sulphone from FBZ, and aldicarb sulphoxide from ALD were found in both species. Aldicarb sulphone was not produced by the hepatocyte preparations from the bullock. The good correlation obtained comparing the in vitro results of FBZ metabolism with published in vivo dat obtained on FBZ kinetics in the same species confirmed the usefulness of in vitro models for predictive analysis of in vivo xenobiotic biotransformations.Abbreviations ALD aldicarb - ALDSON aldicarb sulphone - ALDSOX aldicarb sulphoxide - BSA bovine serum albumin - ID internal diameter - EGTA ethylene glycol bis(-aminoethyl ether) N,N,N,N-tetraacetic acid - FBZ fenbendazole - FBZSON fenbendazole sulphone - HBSS Hanks' balanced saline solution - HPLC high-pressure liquid chromatography - LDH lactate dehydrogenase - MFO mixed function oxidase - NCS newborn calf serum - OXF oxfendazole - WME Williams' Medium E  相似文献   

8.
A trial was carried out in 1-day-old broiler chicks raised for 54 days in floorpens under simulated commercial conditions, but isolated from all extraneous virulent coccidial infections, to demonstrate the safety of Paracox attenuated vaccine administered at the recommended dose when chicks were 7 days old. The vaccine did not adversely affect the water consumption, faecal moisture or litter condition of the broilers. Recycling of the attenuated coccidia occurred in vaccinated birds, oocysts being present in the litter between 5 and 33 days after vaccination; a single peak of oocysts was detectable 5 or 12 days after vaccination. Unvaccinated medicated control birds did not produce oocysts, indicating freedom from both between-pen contamination by the vaccine and invasion of the chicken-house by extraneous coccidial infection. A small proportion (4%) of vaccinated birds had mild coccidial lesions when sampled at 26, 33 or 40 days after vaccination. Despite this, the vaccinated birds performed better than control (unvaccinated, nicarbazin-treated) birds and there was no post-vaccinal check in their weight gain. Their mean finishing weight was 10.4% greater, their food conversion ratio 7.2% lower and their mortality 44.4% lower than the unvaccinated control birds, reflecting the safety of Paracox vaccine.Abbreviation FCR food conversion ratio  相似文献   

9.
A pharmacokinetic study of ampicillin (6 mg/kg intravenous) revealed that the peak concentrations of 17.81±1.25, 5.64±2.24 and 1.09±0.10 g/ml of the drug were attained at 15 min, 30 min and 2 h in plasma, milk and uterine fluid respectively. A therapeutic concentration of 0.1 g/ml was maintained from 15 min–8 h, 15 min–6 h and 30 min–6 h in plasma, milk and uterine fluid. Hence, the drug may be used effectively in mammary gland and uterine infections apart from its use in other systemic infections.  相似文献   

10.
The effects of some 2-adrenoceptor agonists and of the 2-adrenoceptor antagonist atipamezole on food intake and ruminal contractions were studied in dwarf goats. Detomidine, 0.2 µg/kg per min for 10 min, failed to modify food intake during either the first or second observation period (0–30 min and 180–210 min after drug infusion, respectively). Given at a higher dose rate (0.4 µg/kg per min for 10 min), the drug inhibited food consumption during the first observation period, but stimulated food intake during the second period. A similar pattern was observed after IV infusion with medetomidine (0.2 µg/kg per min for 10 min), romifidine (0.4 µg/kg per min for 10 min) or xylazine (1 µg/kg per min for 10 min). The 2-antagonist atipamezole (2 µg/kg per min for 10 min) failed to modify food intake during either the first or second observation period. After treatment with atipamezole, the effects of 2-agonists on feeding behaviour were completely antagonized.The 2-agonists administered at similar dose rates to those used in the food intake experiments induced bradycardia, decreases in body temperature and inhibition of ruminal contractions. The inhibition of ruminal contractions induced by romifidine was partly antagonized by atipamezole pre-treatment. These findings demonstrate that the 2-agonist-induced changes in ruminal contractions do not simply cause changes in feeding behaviour. The drop in body temperature induced by 2-agonists was prevented by atipamezole pre-treatment, whereas the induced bradycardia was not modified by this 2-antagonist.Abbreviations IV intravenous - SEM standard error of the mean  相似文献   

11.
The kinetic profiles of norfloxacin were evaluated in afebrile, febrile and probenecid pre-treated (70 mg/kg orally) febrile goats after a single intravenous (i.v) dose (5 mg/kg). Fever was induced and maintained for 12 h by injecting Escherichia coli endotoxin (0.2 g/kg, i.v.) and repeating it in half the dose (0.1 g/kg) 5 h later. The plasma pharmacokinetic values for norfloxacin were best represented using a two-compartment open model. The peak norfloxacin plasma level of 90.52±3.18 g/ml attained in the probenecid pre-treated febrile goats was higher than that in the febrile (75.46±0.72 g/ml) or afebrile goats (62.25±1.23 g/ml). ClB and K el values were significantly (p<0.01) decreased in febrile compared with afebrile goats. These values were further reduced in febrile goats after probenecid pre-treatment. However, t 1/2 was not affected by the fever-probenecid interaction. Norfloxacin may be used as an infusion with probenecid in caprine diseases where very high plasma levels are required to combat resistant organisms such as Bacteroides.Abbreviations MIC minimum inhibitory concentration - LPS lipopolysaccharide - i.v. intravenous(ly)  相似文献   

12.
A pharmacokinetic study of demeclocycline was carried out following intravenous administration at 5 mg/kg body weight in lactating goats. Demeclocycline appeared within 5 min in plasma, interstitial fluid (isf) and urine, while it appeared at 1 h in milk. Peak concentrations of 21.70±4.06, 2.67±0.23, 5.65±0.45 and 82.23±10.06 g/ml were attained at 5 min and at 6, 8 and 8 h in plasma, isf, milk and urine respectively. A potentially therapeutic concentration of 0.5 g/ml was maintained from 5 min–36 h, 30 min–30 h, 1–36 h and 5 min–48 h in plasma, isf, milk and urine respectively. The drug was detectable in all the above biological fluids for at least 48 h. A low distribution half life (t1/2) of 0.44±0.04 h and a high elimination half life (t1/2) of 19.24±1.22 h denote rapid distribution but very slow elimination of the drug in goats. A high tissue plasma concentration ratio [K12:(K2I–)] of 5.12±0.97 during the elimination phase and a Vdarea of 1.59±0.18 L/kg indicate uniform distribution of demeclocycline in the tissues and body fluids of goats. The dosage regimen for maintaining minimum plasma concentration (C min = MIC) of 0.5, 1.0 and 1.5 g/ml at selected dosage intervals of 12 and 24 h was also calculated.  相似文献   

13.
This paper reports the milk protein polymorphism, the allele frequencies of variants and the possible linkages among various combinations of milk protein phenotypes in the Kangayam cattle of south India. Milk samples from 156 Kangayam cows were typed by starch gel and polyacrylamide gel electrophoresis for caseins and whey proteins, respectively. All the four milk protein components studied, s1-casein, -casein, -lactoglobulin and -lactalbumin, exhibited polymorphism with high allele frequencies of 0.9231±0.0151 for s1-casein C, 0.9263±0.0148 for -casein A, 0.9135±0.0159 for -lactoglobulin B and a relatively high frequency of 0.6218±0.0275 for -lactalbumin A. The mean heterozygosity estimated over all the four milk protein loci was 0.2420. Genetic equilibrium was observed among all the loci studied, except -lactalbumin. Linkage analysis confirmed the non-independence between s1- and -caseins and between caseins and -lactalbumin phenotypes.  相似文献   

14.
The objective of the experiment was to compare the reproductive post-partum performance of beef cows synchronized for oestrus using prostaglandin F2 (PGF2) alone or with a gonadotrophin-releasing hormone (GnRH)-based drug. Fifty-five post-partum lactating Tuli cows were randomly allocated to three groups. Two groups were synchronized using either two injections of PGF2 (500 g Prosolvin per injection) given 11 days apart (group 1), or GnRH (12.5 g Receptal per injection) followed 6 days later by an injection of 500 g PGF2 (group 2). The cows were bred by artificial insemination 12 h after they were observed in oestrus. Group 3 was synchronized as for group 2, but a second injection of GnRH was given 54 h after the PGF2 injection, at which time the cows were bred by artificial insemination (AI) without detection of oestrus. Blood samples were taken from the cows in group 3 and analysed for progesterone concentration to establish which cows were cycling and in oestrus before and at the time of breeding. Detection of oestrus and breeding by AI was done over 60 days. There were no significant differences (p>0.05) among the three groups in the first service and total conception rates. The percentage of cows in oestrus within 10 days of the synchronization treatment was not significantly different (p>0.05) between groups 1 and 2. The progesterone concentrations in the cows in group 3 showed that only those that were cycling at the start of the experiment responded to the synchronization treatment and conceived after fixed-time breeding. These results suggest that combinations of PGF2 and GnRH may be of value in synchronizing oestrus and controlling breeding in Tuli cows. However, the benefit might be greater if only cows that are known to be cycling are bred in this way.  相似文献   

15.
The effect of an intravenous bolus injection of endotoxin, 0.1, 1 or 10 g/kg, on rectal temperature, clinical appearance, haematological parameters, and on gastrointestinal electrical activity was examined in 11 conscious piglets of 4–5 weeks of age, with implanted electrodes in the antrum pylori, duodenum, jejunum and ileum. All doses resulted in a significant and dose-dependent increase in rectal temperature, in pronounced clinical signs and in distinct changes in haematological values. These included shivering, depression, respiratory distress, a leukopenia (0.1 g/kg) or a leukocytosis (1 g/kg) with a shift to the left, an accelerated sedimentation rate and a decreased packed cell volume. Doses of 1 and 10 g/kg induced a transient inhibition of gastroduodenal electrical activity. These results suggest that, in the piglet, endotoxin primarily manifests general clinical signs and that the gastrointestinal effects coincide with these.  相似文献   

16.
The synthetic androgen 19-nortestosterone (-NT) has been used illegally as a growth promoter in cattle production in the European Union. Elimination of -NT and its metabolites in plasma, urine and bile was studied in three cattle with cannulated gallbladders following intramuscular injection at a single site of 500 mg of the laurate ester (NTL) containing 300.5 mg -NT. Using enzyme immunoassay quantification, plasma Cmax of free -NT was 0.5±0.15 g/L (mean±SEM). Concentrations of free -NT in plasma were consistently greater than the assay limit of quantification (0.12 g/L) for 32.7±13.42 days. Mean residence time for free -NT in plasma was 68.5±20.75 days. Following sample preparation by immunoaffinity chromatography, high-resolution GC-MS was used to quantify -NT and -NT in urine and bile. -NT was detected irregularly in urine from two of the three animals post injection. The principal metabolite present in the urine, -NT, was detected for 160.3±22.67 days post injection. Cmax for -NT in urine was 13.7±5.14 g/L. Mean urinary AUC0–183 days for -NT was 845.7±400.90 (g h)/L.In bile, -NT was the only metabolite detected for 174.3±8.67 days post treatment. Cmax for -NT in bile was 40.8±12.70 g/L and mean biliary AUC0–183 days for -NT was 1982.6±373.81 (g h)/L. Concentrations of -NT in bile samples were greater than those in urine samples taken at the same time. The mean ratio of biliary:urinary AUC0–183 days was 3.0±0.72. It is concluded that bile is a superior fluid for detection of -NT following injection of NTL, owing to the longer period during which residues may be detected after administration.  相似文献   

17.
Serum fructosamine concentrations were measured in 11 untreated hypothyroid dogs with normal serum glucose and serum protein concentrations. The fructosamine level ranged between 276 and 441 mol/L (median 376 mol/L; reference range 207–340 mol/L). Nine of the 11 dogs had fructosamine levels above the reference range. The fructosamine levels decreased significantly during treatment with levothyroxine. It is suggested that serum fructosamine concentrations may be high in hypothyroid dogs because of decelerated protein turnover, independent of the blood glucose concentration.  相似文献   

18.
Small intestine was taken from the caudal flexure of the duodenum and the terminal ileum proximal to the ileocaecal fold of 25 horses, 9 with acute grass sickness (AGS), 12 with subacute grass sickness (SAGS) and 12 with chronic grass sickness (CGS). The motility in the samples was measured isometrically either within 1 h of death or after storage for 24 h at 4°C.In control tissue, noradrenaline produced contractions of muscle strips which did not involve a muscarinic cholinergic mechanism and which were unaffected by the 1 antagonist prazosin but were blocked by the 2 antagonist yohimbine. Pretreatment with the antagonist phentolamine prevented the contractile response to noradrenaline and the background contractions either continued at a reduced rate and amplitude or were abolished after a few minutes. Thus, following blockade, noradrenaline reduced the background contraction rate by an effect on inhibitory adrenoceptors. The rate of background contractions in duodenal preparations was significantly greater than that in control ileal preparations.Although cold storage for 24 h caused a reduction in the background contraction rates of the control preparations, there was no effect on the contractile responses to noradrenaline, the associated pharmacology being similar to that of fresh tissue. This suggests that noradrenaline-evoked contraction was not dependent on enteric neural elements.The response to noradrenaline by grass sickness-affected tissue was generally similar to that of tissue from control horses, with an immediate contraction which was 2 sensitive. The contractile response to noradrenaline after propranolol was significantly reduced in the CGS group and there were significant differences between the AGS, CGS and control groups. There was a significant difference between the ileal preparations from the control and SAGS groups in their response to noradrenaline following pretreatment with propranolol.  相似文献   

19.
Measurement of Cortisol Metabolites in Faeces of Ruminants   总被引：8，自引：0，他引：8  
Twenty-one metabolites were detected in faecal samples collected after infusion of (14C)cortisol into the jugular vein of sheep, using high-performance liquid chromatography/radiometric analysis plus mass spectrometry. One group of metabolites had molecular weights of between 302 and 308, and another group of 350, which indicates that the substances have a C19O3 or a C21O4 structure. Therefore, an enzyme immunoassay against 5-androstane-3-o1-11,17-dione-17-CMO:BSA was established. Faecal samples were collected from 10 cows immediately after transport and then during a course in which non-invasive diagnostic procedures were being taught (course 1). For comparison, faeces were sampled from another 5 cows that were being used for teaching invasive procedures (course 2). Six cows from a university farm served as controls. In the animals used in course 1, the highest concentrations of cortisol metabolites were measured immediately after transport to the university (median value: 2.2 mol/kg faeces). During the first 5 days at the university, the concentrations decreased to 0.52 mol/kg (median) and remained at this level during the rest of the course. The median concentration in the samples that were taken during course 2 (collected about 2 months after transport) was 0.48 mol/kg. There was no significant difference in the excretion of cortisol metabolites between these cows and the controls. We conclude from these data that, using the enzyme immunoassay against 5-androstane-3-o1-11,17-dione-17-CMO, we were able to detect transport/novel environment stress but not the potential disturbance that cows experience during diagnostic procedures.  相似文献   

20.
During the past decade it has been discovered that vitamin D3 (cholecalciferol) is converted into 25-hydroxycholecalciferol in the liver and that this compound in converted in the kidney into 1, 25-dihydroxycholecalciferol. These metabolites and particularly 1, 25-dihydroxycholecalciferol, rather than vitamin D itself, have powerful effects on calcium metabolism, stimulating the absorption of calcium from the gastrointestinal tract and the resorption of calcium from bone. A synthetic analogue of these metabolites, 1-hydroxycholecalciferol, is rapidly converted in the liver into 1, 25-dihycroxycholecalciferol. Thus the two metabolites and the synthetic analogue may be valuable for the prevention on treatment of milk fever.The three compounds, when administered in doses ranging from 0.5 to 32g/kg bodyweight increase the concentrations of calcium and phosphorus in the blood plasma of cattle more quickly than much larger doses of vitamin D3. Their principal effect is to stimulate the absorption of calcium from the gastrointestinal tract. At the same time they decrease the plasma concentration of magnesium slightly. Trials of 25-hydroxycholecalciferol and 1-hydroxycholecalciferol in the prevention of milk fever have shown promising results.
Kurzfassung Im vergangenen Jahrzehnt hat man festgestellt, dass das Vitamin D3 (Cholecalciferol) in der Leber in 25-Hydroxycholecalciferol umgewandelt wird und die Nieren diese Verbindung wiederum in 1, 25-Dihydroxycholecalciferol umbilden. Mehr noch als Vitamin D selbst zeigen diese Metaboliten und hier insbesondere das 1, 25-Dihydroxychlecalciferol umfangreiche Auswirkungen auf den Kalziummetabolismus, indem sie die Kalziumabsorption aus dem Magen-Darmtrakt und die Kalziumresorption der Knochen anregen. Ein synthetischer Analogstoff zu diesen Metaboliten, das 1- Hydroxycholecalciferol, wird in der Leber rasch in 1, 25-Dihydroxycholecalciferol umgewandelt. Die beiden Metaboliten und der synthetische Analogwirkstoff könnten daher für die Milchfieberprophylaxe bzw-therapie von Nutzen sein.Werden die drei Verbindungen in Dosen von 0,5 bis 32g/kg Körpergewicht verabreicht, so erhöht sich die Kalzium-und Phosphorkonzentration im Blutplasma der Kühe schneller als bei bedeutend höheren Dosen von Vitamin D3. Ihre Hauptwirkung liegt in der Anregung der Kalzium-absorption aus dem Magen-Darmtrakt. Gleichzeitig bauen sie jedoch auch in geringfügigem masse die Magnesiumkonzentration im Plasma ab. Versuche mit 25-Hydroxycholecalciferol und 1-Hydroxycholecalciferol haben bei der Milchfieberprophylaxe vielversprechende Ergebnisse gezeigt.
Resume Au cours de la dernière décennie, on a découvert que la vitamine D3 (cholécalciférol) se transformait en 25-hydroxycholécalciférol dans le foie et que ce composé se transformait en 1, 25-dihydroxy-cholécalciférol dans le rein. Ces métabolites, et en particulier le 1, 25-dihydroxycholécalciférol, ont, plus que la vitamine D elle-même, des effets puissants sur le métabolisme du calcium: ils stimulent l'absorption du calcium de l'appareil gastrointestinal et la résorption du calcium des os. Une substance homologue synthétique de cés metabolites, le 1-hydroxycholécalciférol, se transforme rapidement en 1, 25-dihydroxycholécalciférol dans le foie. Les deux métabolites et la substance homologue synthétique peuvent donc s'avérer précieux dans la prévention ou le traitement de la fièvre laiteuse.Administrés en doses allant de 0,5 à 32g/kg de poids corporel, ces trois composés augmentent les concentrations de calcium et de phosphore dans le plasma sanguin du bétail plus rapidement que des doses beaucoup plus fortes de vitamine D3. Ils ont pour principal effet de stimuler l'absorption du calcium de l'appareil gastro-intestinal. Simultanément, ils réduisent légèrement la concentration de magnésium dans le plasma. Les essais d'utilisation du 25-hydroxycholécalciférol et du 1-hydroxycholécalciférol pour la prévention de la fièvre laiteuse ont donné des résultats prometteurs.
Riassunto Nel corso dell'ultimo decennio si è scoperto che la vitamina D3 (colecalciferolo) viene trasformata nel fegato in 25-idrossicolecalciferolo, il quale, a sua volta, si trasforma nel rene in 1, 25-diidrossicolecalciferolo. Detti metaboliti, ed in specie l'1, 25-diidrossicolecalciferolo., più che la stessa vitamina D, hanno potenti effetti sul metabolismo del calcio, poichè ne stimolano l'assorbimento da parte dell' apparato digerente e l'anabolizzazione da parte delle ossa. Un composto sintetico analogo di questi metobiliti, l'1, idrossicolecalciferolo, viene rapidamente trasformato nel fegato in 1, 25-diidrossicolecalciferolo. Perciò i due metaboliti e il composto sintetico analogo possono essere utili per la profilassi e la cura della febbre da latte.I tre composti, se somministrati in dosi da 0.5 a 32g/kg peso corporeo, aumentano la concentrazione del calcio e del fosforo nel plasma sanguigno del bestiame più rapidamente di dosi molto maggiori di vitamina D3. Il loro effetto principale è quello di stimolare l'assorbimento del calcio da parte dell'apparato digerente. Contemporaneamente, essi riducono leggermente la concentrazione di magnesio nel plasma. Esperimenti con il 25-idrossicolecalciferolo nella profilassi della febbre da latte hanno dato risultati promettenti.
  相似文献   

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