Decreased vascular reactivity of portal vein in rats with portal hypertension

Abstract

Background/Aims: Vascular hyporesponsiveness in portal hypertension is well documented in the arterial tissue. The present study aimed to investigate the possible changes in the portal vein from portal hypertensive rats. Methods: Portal hypertension was induced by partial portal vein ligation. Fourteen days after surgery, portal veins were removed for contractile study and measurement of cAMP, cGMP and [Ca 2+] i. Results: In vitro tension preparation showed a decreased maximum response to nonrepinephrine in portal vein of portal vein ligated rats (38.3±4.1 vs. 23.4±1.5 mN/mm 2). The pA 2 values of WB4101 and yohimbine ( a 1- and a 2-adrenoceptor antagonist, respectively) were not different between the two groups. Tissue cAMP (14.4±0.9 vs. 12.2±0.7 pmol/mg protein), but not cGMP, content was increased and intracellular calcium [Ca 2+] i levels (247±9 vs. 281±13 nM) were decreased in portal vein ligated rats. Conclusions: These results showed that in portal vein from portal vein ligated rats, vascular hyporesponsiveness and an increase in basal cAMP content and a decrease in basal [Ca 2+] i were observed.