首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 15 毫秒
1.
Four Polwarth castrated male sheep (42 ± 4.4 kg live weight (LW) surgically implanted with chronic indwelling catheters into the mesenteric, portal and hepatic veins, housed in metabolism cages and offered Cynodon sp. hay at rates (g of dry matter (DM)/kg LW) of 7, 14, 21 or ad libitum, were used in a 4 × 4 Latin square experiment to evaluate the effect of the level of forage intake on blood flow and oxygen consumption by the portal‐drained viscera (PDV), liver and total splanchnic tissues (ST). The portal blood flow and the oxygen consumption by PDV linearly increased at increased organic matter (OM) intake. No effect of level of OM intake was obtained for the hepatic artery blood flow and oxygen consumption by liver. As a consequence, the level of OM intake only tended to directly affect hepatic blood flow and oxygen consumption by total ST. Oxygen consumption was linearly and positively related to blood flow across PDV, liver and total ST. The heat production by PDV and total ST, as proportion of metabolizable energy (ME) intake, decreased curvilinearly at increased ME intake. In conclusion, the oxygen consumption by PDV, but not by liver, was directly related to the level of forage intake by sheep. Moreover, when ingested at levels below maintenance, most of ME was spent as heat produced by ST.  相似文献   

2.
OBJECTIVE: To quantify glutamine use by viscera drained by the portal vein in neonatal calves and to determine whether uptake could be stimulated by long-term IV infusion or long-term use of oral supplements. ANIMALS: 4 healthy neonatal calves. PROCEDURE: A femoral artery, jugular vein, and the portal vein were surgically cannulated in each calf. Blood flow in the portal vein was measured, using an ultrasonic transit-time flow probe. Calves were given an IV infusion of glutamine on days 6, 8, and 10 after surgery. Before the first infusion, calves were fed a diet of milk only. The diet was supplemented with glutamine for the second and third infusions. Glutamine was administered via the jugular vein during a 5-hour period. Venous and arterial blood samples were collected every hour for 5 hours. RESULTS: During glutamine infusion, uptake of glutamine by viscera drained by the portal vein increased in association with increased production of ammonia. Glutamine supplementation of the diet did not alter glutamine uptake. Glutamine infusion did not increase viscera uptake of indispensable amino acids. Long-term use of glutamine supplements or infusion of glutamine for periods of more than 1 hour increased glutamine uptake by viscera. Arterial leucine concentration and uptake of leucine by the viscera decreased during glutamine infusion, indicating that leucine became the limiting factor. CONCLUSION: Glutamine administration (supplements or infusions) to calves may require that a mixture of amino acids be provided to improve effectiveness. CLINICAL RELEVANCE: Glutamine may be beneficial in treatments designed to promote intestinal healing in diarrheic calves.  相似文献   

3.
OBJECTIVE: To quantify glutamine use in viscera drained by the portal vein in neonatal calves and to assess the relative nutritional importance of glutamine, glucose, and acetate for enterocytes. ANIMALS: 5 healthy neonatal calves. PROCEDURE: A femoral artery, jugular vein, and the portal vein were surgically cannulated in each calf. Blood flow in the portal vein was measured by use of an ultrasonographic transit-time flow probe. A series of solutions was infused on 4 days for each calf. On the infusion days, acetate, glucose, glutamine, and saline (0.9% NaCl; control) solutions were administered IV during 1-hour periods via the jugular vein. Venous and arterial blood samples were collected during the last 15 minutes of each 1-hour infusion. RESULTS: Uptake of glutamine and glucose by viscera drained by the portal vein was 0.3+/-1.1 and 1.9+/-3.1 micromol/kg0.75/min, respectively, during saline infusion. During acetate, glucose, and saline infusions, glucose was a greater source of energy for the intestines than was glutamine. However, during glutamine infusion, uptake of glutamine by viscera drained by the portal vein increased significantly (29.9+/-11.2 micromol/kg0.75/min), which was associated with an increase in ammonia production (7.0+/-0.5 micromol/kg0.75/min). Toxicosis was not associated with IV administration of glutamine. CONCLUSION: Glutamine infusion resulted in an increase in glutamine uptake by viscera drained by the portal vein, which was associated with an increase in ammonia production and a slight increase in oxygen consumption. CLINICAL RELEVANCE: These solutions may be used to develop treatments that enhance healing of intestines of diarrheic calves.  相似文献   

4.
Surface oxygen tension (PSO2) was measured in dogs during experimental manipulation of the portal vein and hepatic artery, and during surgery to correct portosystemic shunting. There was no alteration in PSO2 of liver, pancreas, duodenum, or jejunum during partial (50%) or complete reduction of hepatic artery flow. After 100% reduction in portal vein blood flow, PSO2 was lower in jejunum, duodenum, and liver. With 50% reduction in portal flow, PSO2 was significantly decreased only in jejunum. In six dogs with single extrahepatic shunts, there was a significant correlation between portal pressure and jejunal PSO2. It was concluded that measurement of visceral organ PSO2 represents an accurate noninvasive means of obtaining objective data on the effect of reduction in hepatic blood flow on perfusion of other select splanchnic organs.  相似文献   

5.
Measurement of hepatic oxygen extraction was performed on six healthy Greyhound dogs over a two hour period. The Greyhounds were anaesthetised and a right subcostal surgical incision performed. Ultrasonic flow transducers were used to measure flow rate in the hepatic artery and the portal vein. The blood oxygen tensions in arterial blood and in the portal and hepatic veins were also measured. Hepatic oxygen extraction remained stable throughout the study, despite a steady decline in arterial blood pressure. The methodology described in this study provides a direct measure of oxygen uptake by the liver in the dog and could readily be used to investigate hepatic uptake of drugs.  相似文献   

6.
在4头门静脉、肝静脉、肠系膜静脉和股动脉上安装血管导管的绵羊中研究了克伦特罗（CL,0.8 mg/kgBW,肠系膜静脉给药,每天2次,连续5 d）对其肝脏生长代谢的影响。结果表明:CL对肝脏血流量影响较小。而在CL作用下绵羊血浆中尿素氮水平明显下降,肝静脉和门静脉血液尿素氮流量分别减少16.86％（P<0.01）和15.51％（P<0.05）。肝静脉多肽流量在CL处理期也较对照期下降38.71％（P<0.01）,门静脉处多肽水平处理期则与对照期相当。克伦特罗还增加绵羊肝脏IGF-I的合成和分泌,门静脉和肝静脉中的增加幅度分别为38.84％（P<0.01）和33.18％（P<0.01）。提示CL可通过增强对绵羊肝脏氮的储留及肝脏IGF-I的合成和分泌从而促进机体的生长代谢。  相似文献   

7.
Detailed knowledge of the vascular anatomy is important for improving surgical approaches to the liver. Twelve canine livers were skeletonized to describe the anatomy of their portal and hepatic veins in details. Our data suggest that the liver can be divided into two sections, three divisions, seven lobes and two to four sub‐lobes. This differs from the classic division into four lobes, four sub‐lobes and two processes. The right section was perfused by the right portal branch and drained by independent hepatic veins, while most of the left section, perfused by the left portal branch, was drained by the main hepatic vein deriving from the middle and the left hepatic vein confluence. Part of the right medial lobe, and in some cases the papillary process of the caudate lobe, drained directly into the caudal vena cava. A proper right hepatic vein draining blood from more than one lobe was never observed. Portal connections between the quadrate and the left medial lobe were frequently recorded. Two sub‐lobes with different portal blood supply and venous drainage could be identified in the right lateral (33.3% of cases) and the left lateral (100% of cases) lobes. From our results, the classic nomenclature of the liver lobes does not reflect their vascularization. Based on similarities between canine lobes and human segments, a new nomenclature is possible and may be less confounding in surgical settings.  相似文献   

8.
Control of blood flow in the renal portal circulation of turkeys given epinephrine was evaluated by determining the distribution of injected radiopaque contrast medium within the portal circulation. Radiopacity in the region of the renal parenchyma and/or the caudal renal portal vein was increased in each of the 6 birds after epinephrine (4.0 micrograms/kg of body weight) was injected into the wing vein. In 1 bird, the contrast medium also was distributed into the mesenteric vein. Thus, epinephrine not only induced flow of blood from the pelvic limb (leg) to the kidneys, but to the abdominal viscera as well. Regulation of the patency of the renal portal valve is thought to be one means by which renal portal blood flow is controlled. However, epinephrine had no consistent effect on the valve. Thus, epinephrine seemed to control renal portal blood flow and, perhaps, blood flow to other abdominal viscera at sites other than the renal portal valve.  相似文献   

9.
OBJECTIVE: To determine changes in splanchnic oxygen extraction ratio during experimentally induced portal hypertension in dogs. ANIMALS: 6 clinically normal dogs. PROCEDURE: Standard midline laparotomy and median sternotomy were performed in anesthetized dogs. Baseline measurements of arterial blood pressure, aortic blood flow, portal vein blood flow, and portal vein pressure were acquired, and arterial, venous, and portal vein blood samples were obtained to determine systemic and splanchnic oxygen extraction ratios. The portal vein was gradually occluded until a pressure of 18 cm of H2O was reached; this pressure was maintained for 30 minutes, and measurements and collection of blood samples were repeated. RESULTS: Portal vein blood flow decreased significantly from 457 +/- 136 ml/min before to 266 +/- 83 ml/min after induction of portal hypertension. Oxygen content in the portal vein significantly decreased from 12.3 +/- 1.85 to 8.2 +/- 2.31%, and splanchnic oxygen extraction ratio significantly increased from 15.8 +/- 6.2 to 37.4 +/- 10.9% during portal hypertension. There was a significant inverse correlation between portal vein blood flow and splanchnic oxygen extraction ratio at baseline and during portal hypertension. CONCLUSIONS AND CLINICAL RELEVANCE: An increase in splanchnic oxygen extraction ratio is evident with partial attenuation of the portal vein and the concurrent decrease in portal vein blood flow. Correlation of oxygen extraction ratio with portal vein blood flow may be a more important indicator for determination of an endpoint to prevent congestion and ischemia of the gastrointestinal tract and pancreas during ligation of portosystemic shunts.  相似文献   

10.
Changes in net portal and hepatic nutrient flux and oxygen consumption in response to 3-d abomasal casein infusions were studied in seven multicatheterized beef steers. Steers were fed 4.3 kg DM/d of a high-concentrate diet in 12 equal meals. Blood flow (para-aminohippurate dilution) and net flux (venoarterial concentration difference x blood flow) across portal-drained viscera (PDV) and hepatic tissues were measured on d 3 of the abomasal infusions. In two experiments, the response to 300 (300C) and 150 (150C) g casein/d were compared, respectively, to a control water infusion. The 300C increased (P less than .05) arterial blood concentrations of alpha-amino N (AAN), urea N and ammonia; 150C increased (P less than .05) arterial urea N. Urinary urea N excretion was increased (P less than .01) by 300C and 150C. Although 300C increased net PDV release of AAN (P less than .07) and alanine (P less than .10), there was no net change in total splanchnic (TSP) flux due to an increased net hepatic uptake of AAN (P less than .01) and alanine (P less than .05). Net PDV glucose flux was decreased (P less than .05) by 300C, but net hepatic glucose flux was not affected by either level of casein. The 150C increased TSP oxygen consumption (P less than .05) and hepatic oxygen extraction (P less than .10). Approximately 26 and 30% of the casein N infused abomasally appeared in the portal blood as AAN for 150C and 300C, respectively. The sum of net PDV ammonia and AAN fluxes accounted for 47 and 88% of the N infused for 150C and 300C, respectively. These data emphasize the importance of intestinal and liver tissues in regulating the flux of nitrogenous compounds absorbed from the diet.  相似文献   

11.
在 4头门静脉、肝静脉、颈静脉、肠系膜静脉和股动脉上安装血管导管的绵羊中研究了克伦特罗 (CL ,0 8mg/kgBW ,肠系膜静脉给药每天 2次 ,连续 5d)对其肝脏物质代谢的影响。结果表明 :CL可增加绵羊肝脏中的VFA流量 ,其中门静脉处乙酸、丙酸和丁酸的流量分别较对照期增加 19 4 9% (P <0 .0 1)、2 0 2 % (P >0 .0 5 )和4 5 5 % (P >0 .0 5 ) ,而肝静脉处VFA流量两期水平接近。CL也提高肝脏中葡萄糖的异生作用 ,在肝静脉处血中葡萄糖流量上升了 2 5 96 % (P <0 .0 1)。门静脉处血中葡萄糖循环水平也相应提高。此外在CL作用下肝静脉处胰岛素水平也较对照期有所下降。提示CL可增加进入绵羊肝脏中VFA的流量并促进肝脏对VFA的吸收和利用。通过降低胰岛素水平或对肝脏的直接作用CL还可增加绵羊血中葡萄糖的水平  相似文献   

12.
Surgical procedures are described for chronic cannulation of portal vein, ileal vein, abdominal aorta, and carotid artery in pigs. Silastic or Micro-Renathane tubing was used for cannulating portal vein and ileal vein, while carotid artery was cannulated with Micro-Renathane tubing. The lumen of Micro-Renathane tubing was coated with tri-dodecylmethyl ammonium chloride (TDMAC)-heparin complex. The abdominal aorta was cannulated via saphenous artery with vinyl tubing. This allows simultaneous collection of blood samples from hepatic portal vein and systemic artery (carotid or abdominal aorta) and continuous infusion of p-aminohippuric acid (PAH) into ileal vein. The constant PAH infusion provided an indicator-dilution method for estimating the blood flow rate in portal vein. In 13 pigs weighing 54 +/- 2.8 kg, the mean portal vein blood flow rate during the 8-h postprandial period was estimated to be 1,979 ml X min-1 X pig-1 or 37.8 ml X min-1 X kg-1 body weight. By simultaneously measuring the concentration of nutrients and metabolites in the portal and systemic arterial blood and multiplying porto-arterial differences by the estimated portal vein blood flow rate, the net absorption of nutrients (except long-chain fatty acids) and metabolites into hepatic portal system in conscious swine can be quantified.  相似文献   

13.
Throughout its life, a 1-year-old Doberman Pinscher dog had had gastrointestinal disorders and episodes of circling. It was less active than its littermates, and it usually seemed lethargic. When 3 months old, the pup had been anesthetized for ear cropping and it had remained anesthetized for 32 hours. Behavioral problems were apparent when the dog was 11 months old. Two weeks later the behavioral problems accentuated to the point that the dog developed "temper tantrums" and became aggressive toward its owner. On the basis of clinicopathologic and contrast radiographic findings, hepatoencephalopathy due to persistent patent ductus venosus was diagnosed and the dog was euthanatized. Situs inversus abdominalis and multiple vascular anomalies were found at necropsy. Gross and microscopic studies of the viscera were correlated with corrosion casts of the vasculature. In addition to changes in organ position, 3 spleens and malformation of the pancreas were observed. Vascular anomalies were: (1) The portal vein was contiguous with the common hepatic vein by way of a patent ductus venosus; branches of the portal vein were not given off to the liver; (2) the caudal vena cava was continued by the azygos vein, and a cranial segment of the caudal vena cava was absent; (3) the hepatic artery was larger than normal; (4) the left gastric artery arose anomalously from the cranial mesenteric artery; and (5) histologic and radiographic study of the liver did not reveal any interlobular branches of the portal vein; however, hypoplastic branches of the gastroduodenal vein did enter the liver and were demonstrated on a corrosion cast.  相似文献   

14.
Data from six experiments were used to describe sources of variation in blood flow through portal-drained viscera and liver of 33 steers that were fed equal-sized meals every 2 h. The experiments were designed to create "steady-state" conditions under which response to various dietary or physiological treatments was assessed. Sums of squares for blood concentration of blood flow marker, venoarterial differences in blood flow marker, and blood flow were divided into variation attributable to steer; period (or time); the steer x period interaction; sampling days within steer and period; and replications (or samplings) within day, steer, and period. Steer was the largest single source of variation in arterial concentration of blood flow marker, accounting for from 42 to 80% of sums of squares among the experiments. However, replication within day, steer, and period accounted for more variation than steer in portal or hepatic blood flow in four of the six experiments. When balanced for treatment effects, steer accounted for 59%, period and the steer x period interaction accounted for 14%, and replication accounted for 27% of variation in portal blood flow. Corresponding percentages for hepatic blood flow were 45, 20, and 35%. I conclude that steer and replication within steer x period cells in a matrix of treatments are the two largest sources of variation and that there is more variation among samples on a given day within steer x period cells than among days in the same cells.  相似文献   

15.
We compared two techniques for measuring blood flow through portal-drained viscera (PDV) of beef steers and measured portions of cardiac output and total oxygen uptake attributable to PDV and hepatic tissues. Four steers (198 +/- 2 kg), equipped with chronic catheters in appropriate vessels, a transit-time ultrasound probe around the hepatic portal vein and a temporary cardiac output thermodilution catheter, were fed a 60:40 hay: concentrate diet. Treatments, designed to alter blood flow, were: 12 equal meals every 2 h (CNTL); CNTL plus 2 mg clenbuterol in one meal (CLEN); and a 65-h fast (FAST). Blood flow through PDV was measured by dilution of p-aminohippurate (PAH) and transit-time ultrasound. Hepatic blood flow was measured by PAH dilution and cardiac output was measured by thermodilution. Blood flow measured by transit-time ultrasound was consistently slower (45%, P less than .01) than blood flow measured by PAH dilution. Necropsy revealed anatomical constraints that precluded proper placement and function of the flow probes. Cardiac output (liters/h) was greater (P less than .05) for CLEN (3,082) than for CNTL (1,655) or FAST (1,047). Percentage of cardiac output flowing through PDV and hepatic tissues was less (P less than .05) for CLEN (23 and 24%) than for CNTL (31 and 38%) or FAST (32 and 38%). Whole body oxygen uptake (mmol/h) was greatest (P less than .05) for CLEN (4,220), intermediate for CNTL (2,999) and least for FAST (1,965). Percentage of oxygen uptake attributable to hepatic tissues was greater (P less than .05) for FAST (31%) than for CLEN (18%), with CNTL intermediate (24%). Percentage of oxygen uptake attributable to PDV (22%) was not affected (P greater than .05) by treatments.  相似文献   

16.
Portal blood flow was measured with duplex Doppler ultrasound in ten normal dogs and in ten dogs with hepatic cirrhosis induced by common bile duct ligation 4 weeks previously. Mean portal blood flow velocity in the 10 dogs with experimentally induced hepatic cirrhosis was markedly reduced (9.2 ± 1.70 cm/sec vs. normal 18.1 ± 7.6 cm/sec, p < 0.01). Mean portal blood flow was also significantly decreased compared to normal (17.2 ± 4.9 cc/min/kg versus normal 31.06 ± 9.1 cc/min/kg, p < 0.01) while portal vein diameter remained unchanged. The dogs with induced hepatic cirrhosis developed extensive extrahepatic portosystemic shunting that was confirmed at necropsy. It was concluded that decreased portal velocity and portal flow which resulted from hepatic cirrhosis was detectable noninvasively with Doppler ultrasound.  相似文献   

17.
A dilated, tortuous blood vessel was identified sonographically in the right medial liver lobe in a puppy with severe ascites. This vessel was thought to represent the dilated right medial portal vein branch. Using pulsed wave Doppler ultrasonography, retrograde, abnormally pulsatile flow was detected in both the dilated right medial portal vein branch and the main portal vein. The right medial liver lobe was surgically resected then fixed in formalin. Silicon rubber was injected and outlined the connection between the portal vein and hepatic artery.  相似文献   

18.
The time course and quantity of 3-methylindole (3MI) and indole absorbed after oral administration of L-tryptophan (TRP) was determined in 2 steers. The relationship between the appearance of 3MI and indole in the rumen and blood plasma to absorption of 3MI and indole was also studied. Two Hereford X Angus steers with portal vein, mesenteric vein, and femoral (steer 1) or iliac (steer 2) artery catheters were used. Absorption rates from the portal drained viscera (net absorption) of 3MI and indole were determined by the product of portal and arterial concentration difference and blood flow. Blood flow was determined by primed continuous infusion of p-aminohippuric acid into a mesenteric vein. Three absorption measurements 30 minutes apart were taken at midpoint times of 0, 12, 24, 36, and 48 hours after oral administration of 0.4 g of TRP/kg of body weight. Steer 1 was dosed twice resulting in a total of 45 absorption measurements. Net absorption of 3MI and indole peaked at an average of 1.05 and 0.81 g/hr, respectively. By 48 hours, 29.2% and 15.3% of the TRP dose were accounted for by 3MI and indole absorption, respectively. Closed system in vitro incubations of TRP with ruminal fluid from the same 2 steers resulted in a TRP to 3MI conversion of 23.2% and a TRP to indole conversion of 10.7%. Net absorption of 3MI and indole closely followed and was correlated with concentration of 3MI and indole in ruminal fluid and blood plasma.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

19.
Portal hypertension resulting in ascites and portosystemic shunts leading to hepatoencephalopathy are major clinical manifestations of hepatic circulatory disease. Diffuse liver disease impairing sinusoidal blood flow can induce portal hypertension, portosystemic shunts, or both. The liver may also be involved secondarily in posthepatic hypertension and become the site of ascitic fluid formation. Portosystemic shunts may or may not be associated with portal hypertension. Selective catheterization of the hepatic and portal veins permits one to record pressures and to outline gross and subgross vascular anomalies by injecting contrast medium. Sequential pressure recordings in the caudal vena cava, in a free and wedged hepatic vein position, in the splenic pulp, and directly in the portal vein are the bases for the differentiation of prehepatic, liver-induced, and posthepatic portal hypertension. In addition to localizing the disease process along the postcaval-portal vein axis, pressure measurements are a reliable basis for the prognosis and selection of the most appropriate therapy. In dogs with portacaval shunts, wedge hepatic vein pressure recordings assist in the detection of hepatic sinusoidal anomalies that limit blood flow and preclude surgical ablation of the shunts. The various technics and their suitability for direct and indirect portal vein pressure recording are described and evaluated. Normal portal vein pressure values in 11 dogs and two cats, using different technics, are provided. The clinical usefulness of the various technics of pressure recording and angiography was illustrated in ten dogs with ascites, hepatoencephalopathy, or both.  相似文献   

20.
Four healthy, fully conscious, 50- to 80-kg Yucatan miniature swine were fitted with carotid artery and jugular, portal, and hepatic vein catheters and hepatic artery and portal vein flow cuffs to determine transhepatic kinetics and insulin secretion. Three days later, after a 3-hour control period, the pigs were given IV sodium dichloroacetate (30 mg/kg of body weight as a bolus and 30 mg/kg/hr, as an infusion) for 6 hours. Arterial lactate concentrations decreased during the dichloroacetate infusion, but pyruvate concentrations were unaltered. The whole body rate of appearance and disappearance of glucose decreased, but plasma glucose concentrations did not change markedly. Limb skin surface temperatures increased, indicating a peripheral vasodilatory effect. Dichloroacetate had little effect on mean arterial pressure and hepatosplanchnic blood flow. Dichloroacetate may be effective as a hypolactatemic agent for lactic acidosis in pigs.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号