Hemodynamic function in dogs with chronic obstructive jaundice: effects of radiocontrast medium

Chronic obstruction of the biliary tract alters circulatory function. The effects of radiocontrast medium (iothalamate meglumine) on systemic and renal hemodynamics were studied in normal dogs and dogs with chronic common bile duct ligation (CBDL). After intravenous injection of radiocontrast, cardiac output and stroke volume were not altered in normal and CBDL dogs; arterial pressure was stable in normal dogs but decreased significantly in CBDL dogs and was accompanied by reduced systemic vascular resistance. In normal and CBDL dogs the renal hemodynamic responses to radiocontrast medium were characterized by initial vasoconstriction (independent of renal renin release) and later vasodilation. This vasodilatation in CBDL dogs was particularly striking as it occurred despite reduced renal perfusion pressure and the augmented renin-angiotensin system. Inhibition of prostaglandin synthesis with indomethacin in CBDL dogs abolished both the hypotensive and the renal vasodilator responses to radiocontrast medium. We conclude that enhanced prostaglandin activity contributes to the labile hemodynamic function noted in obstructive jaundice.