The effect of bile duct manipulation on cardiovascular responsiveness: in vivo studies.

Cholestasis depresses cardiovascular function and responsiveness. In a previous study, the 3-day bile duct manipulated (BDM) rat was validated as the appropriate control for studying in vitro vascular neuroeffector mechanisms in cholestasis. The present study reports the findings on the effect of BDM on cardiovascular function and responsiveness in conscious rats. Cardiovascular responsiveness was assessed by measuring the in vivo pressor responses to a 90 degrees head-up vertical tilt, a controlled hemorrhage, and to intravenously infused norepinephrine, tyramine, the indirectly acting sympathomimetic drug, isoproterenol, the nonselective beta-adrenoceptor agonist, angiotensin I, and angiotensin II. The concentrations of catecholamines and plasma renin activity measured in plasma samples obtained from conscious chronically arterial catheterized BDM rats were compared to identical data obtained from rats in which the bile duct was not manipulated. There were no differences in cardiovascular responsiveness to any of these procedures or drug infusions between the two groups of rats. Plasma catecholamine concentrations and renin activities in the BDM rats were not significantly different from control rats. Although no differences in cardiovascular responsiveness between BDM and control rats were observed, these data confirm the choice of the BDM as the control group for experiments assessing the effects of cholestasis on cardiovascular responsiveness.