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1.
We used isolated equine digital arteries to study the vasodilatory mechanism of isoxsuprine, and fowl caecum preparations to investigate the affinity of the drug for beta-adrenoceptors. Isoxsuprine is a potent vasodilator of arterial smooth muscle that has been precontracted by an alpha-adrenoceptor agonist such as noradrenaline (log EC50 = -6.33 [-5.98; -6.68]). The present study indicates that its effect is due to alpha-adrenoceptor blockade since: (1) after a long lasting exposure to cumulative doses of isoxsuprine the vasoconstricting action of noradrenaline cannot be restored; (2) isoxsuprine does not promote relaxation on preparations precontracted by PGF2alpha; (3) isoxsuprine shifts the dose-response curve of noradrenaline to the right; and (4) its affinity (pK(B) = 6.90 [6.60; 7.20]) in this experiment is comparable to that in noradrenaline-precontracted preparations and is 14 times lower than that of the selective alpha1-adrenergic antagonist prazosin [pK(B) = 8.04 (7.40; 8.68]). The affinity of isoxsuprine for beta-adrenoceptors was 100 times lower than that of isoprenaline when tested on fowl caecum. This preparation has a large beta-adrenoceptor and negligible alpha-adrenoceptor population concerned with the control of smooth muscle motility. Our data suggest that the alpha-mediated effect of isoxsuprine on horse arterial smooth muscle is due to higher affinity of the drug for alpha- than beta-adrenoceptors rather than low concentration or functionality of beta-sites at this site. According to these data, pure beta2-agonists seem to be more profitable tools to determine vasodilation of the arterial bed in horses legs. 相似文献
2.
The risk related to the presence of residues in food of animal origin has to be carefully evaluated and it is important to distinguish between the residues of veterinary drugs and environmental contaminants. The first are easily monitored and only difficultly and occasionally exceed MRL concentrations, whereas the second ones can have prolonged and high level exposures. The Safety Margins of environmental contaminants are thus lower, and the risk increases for high level consumers. It is therefore important to ovoid transfer of pollutants to food of animal origin, especially when local contamination occur.
相似文献3.
Spotti M Fracchiolla ML Arioli F Caloni F Pompa G 《Veterinary research communications》2005,29(6):507-515
A recent approach to the problem of contamination of agricultural products by aflatoxin B1 (AFB1) is to add non-nutritional adsorbents to animal diets in order to sequester ingested aflatoxins. We conducted in vitro experiments to develop a rapid and cheap model using ruminal fluid to assess the ability of sorbent materials to bind AFB1. Seven sorbents (hydrated sodium calcium aluminosilicate; clinoptilolite; zeolite; two types of bentonite; sepiolite; and
PHIL 75), commonly added to bovine diets were incubated in water and ruminal fluid in the presence of AFB1. Hydrated sodium calcium aluminosilicate, sepiolite and one of the bentonites bound 100% of the AFB1 in the presence of both ruminal fluid and water; clinoptilolite bound about 80% of AFB1 in both liquids; whereas the affinities for the mycotoxin of zeolite (50%) and the other sample of bentonite (60%) in water
seem to be increased by about 40% in ruminal fluid incubations. PHIL 75 had the poorest binding ability: about 30% in water
and 45% in ruminal fluid. In view of the differences in toxin binding in water and ruminal fluid, it is preferable to use
the ruminal fluid model for the in vitro pre-screening of sorbent materials potentially useful as adjuvants to ruminant feeds. 相似文献
4.
L. Chiesa S. Pavone E. Pasquale R. Pavlovic S. Panseri A. Valiani F. Arioli E. Manuali 《Journal of animal physiology and animal nutrition》2017,101(5):893-903
The Chianina, one of the oldest and most important cattle breeds of Italy, is now reared all over the world. The Chianina has been known and appreciated since ancient times because, from a nutritional point of view, its meat has no proper rivals. To date, studies have been performed to evaluate the genetic profile of the breed, but knowledge about the chemical profile is generally lacking. Due to the increased interest from farmers regarding breeding of the Chianina, this study proposes a preliminary evaluation of main endogenous urinary corticosteroids (cortisol and cortisone) and most commonly used synthetic one (dexamethasone). Moreover, after recent findings regarding the presence of endogenous prednisolone in the urine of more popular breeds, particular attention was given to analysis of the presence of prednisolone and prednisone, as well. For this aim, the urine samples of 12 young cows and 30 young bulls was collected at the farms and analysed using a fit‐for‐purpose LC‐MS/MS method. The preliminary results of this study show that prednisolone was found only in Chianina females (3 out of 12). Cortisol and cortisone were found at concentrations that showed a high inter‐individual variability, and that were higher in female urine compared to that of males. 相似文献
5.
The risk related to the presence of residues in food of animal origin has to be carefully evaluated and it is important to distinguish between the residues of veterinary drugs and environmental contaminants. The first are easily monitored and only difficultly and occasionally exceed MRL concentrations, whereas the second ones can have prolonged and high level exposures. The Safety Margins of environmental contaminants are thus lower, and the risk increases for high level consumers. It is therefore important to ovoid transfer of pollutants to food of animal origin, especially when local contamination occur. 相似文献
6.
Ditte G Christiansen Christian Jakob Martina Arioli Sandra Roethlisberger Heinz-Ulrich Reyer 《BMC ecology》2010,10(1):14
Background
The role of differential selection in determining the geographic distribution of genotypes in hybrid systems has long been discussed, but not settled. The present study aims to asses the importance of selection in structuring all-hybrid Pelophylax esculentus populations. These populations, in which the parental species (P. lessonae with genotype LL and P. ridibundus with genotype RR) are absent, have pond-specific proportions of diploid (LR) and triploid (LLR and LRR) genotypes. 相似文献7.
The risk related to the presence of residues in food of animal origin has to be carefully evaluated and it is important to distinguish between the residues of veterinary drugs and environmental contaminants. The first are easily monitored and only difficulty and occasionally exceed MRL concentrations, whereas the second ones can have prolonged and high level exposures. The Safety Margins of environmental contaminants are thus lower, and the risk increases for high level consumers. It is therefore important to ovoid transfer of pollutants to food of animal origin, especially when local contamination occur. 相似文献
8.
Belloli C Badino P Arioli F Odore R Re G 《Journal of veterinary pharmacology and therapeutics》2004,27(4):247-254
Radioligand binding studies and functional assays on isolated smooth muscle preparations were performed in order to obtain a biochemical and functional characterization of the beta-adrenoceptor (beta-AR) subtypes involved in regulation of the smooth muscle relaxation of the calf's common digital artery. The results indicate that the common digital artery possesses two beta-AR populations (40% beta(1) and 60% beta(2)) and the beta(2)-subtype appears to predominate as far as function is concerned. Only the beta(2)-AR agonists clenbuterol and fenoterol caused dose-related relaxant effects, antagonized by propranolol, when tested in preparations precontracted both with PGF(2alpha) (1.4 x 10(-5) m) and noradrenaline (1.2 x 10(-6) m). In noradrenaline precontracted preparations the beta(1)-AR selective agonists dobutamine and xamoterol caused vasodilation which was not antagonized by (+/-)propranolol. While the functional relaxant effects of dobutamine may be attributed to its potent competitive alpha-AR blocking activity, further investigations are required to explain the effect of xamoterol. The vasodilator effect of (+/-)isoproterenol was irregular. The recorded contractile effects, mainly at dosages greater than 10(-6) m, suggest the loss of drug selectivity for beta-AR and alpha-AR activation. Indirect evidence indicates that the alpha-adrenoceptor (alpha-AR) population in this tissue which produces a strong contraction is functionally dominant over the beta-AR, suggesting limited therapeutic benefit for beta-AR drugs to control blood flow disorders in the calf's distal limb. 相似文献
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