1. The distribution of intrarenal blood flow has been measured using the 133Xe-washout technique in thirteen baboons 2 weeks after ligation of the common bile duct. 2. In comparison with eight sham-operated baboons, there was a signifigant decrease in the percentage distribution of blood to the cortex, although the rate of flow was unchanged. These changes were accompanied by a significantly increased flow rate and percentage distribution of flow through the juxtameduallary circulation. 3. In a further five baboons treated in the same way, various doses of noradrenaline were infused into the renal artery. In these animals there was an enhanced pressor response to noradrenaline, and this effect was completely abolished by an alpha-adrenoreceptor blocking agent (phenoxybenzamine). The beta-adrenoceptor blocking drug (propranolol) had no such effect. 4. This enhanced response was not seen when noradrenaline was infused into three sham-operated baboons. 5. These observations suggest that the alterations in renal perfusion in obstructive jaundice may be due to an increase renovascular sensitivity to circulating catecholamines and an enhanced alpha-adrenoceptor activity.
Alterations in renal perfusion have been shown in a variety of liver diseases. We have examined the possibility that the syndrome is due to a renal vascular hypersensitivity to noradrenalin (NA). Isolated perfused kidneys and segments of rabbit femoral artery were used. Potentiation of the pressor effects of injected NA occurred in all (five artery and five kidney) preparations when jaundiced baboon plasma was perfused. These changes were significant (P less than 0.05) in nine out of the ten experiments. Controls to which normal baboon plasma was administered showed no such change. No correlation was found between the degree of NA potentiation and the plasma concentrations of bilirubin (total and conjugated), serum glutamic oxaloacetic transaminase, blood urea nitrogen, serum glutamic pyruvic transaminase, alkaline phosphatase, Na+ ions or K+ ions in the jaundiced plasma. Plasma renin levels were not significantly changed. When arteris were perfused with Krebtentiation of NA was found. Perfusion of sodium taurocholate or sodium deoxycholate (400 mug/ml) yielded no potentiation. Thus, the altered renal perfusion associated with jaundice may be attributed to a potentiated pressor response to NA which may be caused by an increased level of cholesterol carried on the beta-lipoprotein.
SUMMARY The effects of intracarotid infusions of noradrenaline on the cerebral vasculature were studied in seven baboons with bile duct ligation. Infusion of 8 ,ug and 16 Mg/min of noradrenaline resulted in a significant decrease in cerebral blood flow in the jaundiced animals. In normal baboons, these doses produced cerebrovascular dilatation. These results indicate that there is an increased cerebrovascular sensitivity to noradrenaline in the obstructive jaundice which follows bile duct ligation. It is postulated that noradrenaline smooth muscle uptake mechanisms are disturbed allowing a greater concentration of the amine at the receptor sites.Recent studies in the baboon have indicated that there is an increased renovascular sensitivity to noradrenaline with bile duct ligation (Bloom, Bomzon, Rosendorff, and Scriven, 1974). Similarly, experiments on an isolated artery preparation have shownpotentiationofthepressoreffectsofnoradrenaline by plasma obtained from these baboons (Bloom, McCalden, and Rosendorff, 1975a). These results suggest that there is a heightened pressor response to circulating catecholamines in the obstructive jaundice following bile duct ligation.The present study was evolved to examine the possibility that a similar hypersensitivity to noradrenaline exists in the cerebral vascular bed in baboons with duct ligation. This may elucidate some of the unexplained symptoms of cerebral dysfunction in hepatic disease (Sherlock, 1968 mg/kg pentobarbitone sodium (Nembutal, Abbott). The animals were then intubated and anaesthesia was maintained with a 3:2 mixture of oxygen and nitrous oxide with similar quantities of barbiturate given to each group as required. A catheter was introduced into the femoral artery to measure intraarterial blood pressure via an electromanometer (Statham P23AA) and to enable arterial blood sampling for determinations of PaCO2, PaO2 and pH on an Instrumentation Laboratories' blood gas analyser (IL 313). The right carotid bifurcation was exposed and a fine catheter was inserted into the lingual artery until its tip just entered the external carotid artery. The external carotid artery and all its remaining branches were then ligated. Cerebral blood flows were measured by an intracarotid '33xenon washout technique. A bolus of 30 ,Ci of 133xenon in 0.2 ml of saline was injected into the lingual catheter and was washed retrograde down the external carotid artery into the internal carotid.The cerebral uptake and clearance of 133Xe was monitored using a 5-cm diameter sodium iodide detector mounted posteriorly over the parietal region. A high degree of collimation was used to exclude the possible radiation arising from noncerebral orbital tissues. This was confirmed by the absence of a third flow component (extracranial perfusion) in the clearance curves. After the initial peak of activity the clearance data were recorded for at least 15 min in digital form with a Nuclear Enterprises' data logging system. When exceptionally slow flows were found this record was extended to 20 minutes...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.