CHRONIC ADMINISTRATION OF OCTREOTIDE INCREASES VASCULAR RESPONSIVENESS IN RATS WITH PORTAL-HYPERTENSION

1. has been reported that octreotide partially corrects the hyperdynam ic state in patients and animals with portal hypertension, The aim of the present study was to investigate whether chronic administration of octreotide can increase vascular responsiveness in rats with portal h ypertension. 2. Portal hypertension was induced by partial portal vein ligation, Octreotide was given for 9 days subcutaneously (100 mu g/kg every 12 h) starting 1 day before ligation. The aorta and mesenteric artery were then removed to study contraction after pressure recording . 3. Octreotide treatment significantly reduced portal and plasma gluc agon concentrations with the vehicle-treated group. Both phenylephrine and vasopressin induced concentration-dependent contractile responses in the aorta and mesenteric artery from both groups. The maximum cont ractile responses to phenylephrine and vasopressin in aorta and mesent eric artery were significantly greater in the octreotide-treated group than in the vehicle-treated group, The EC(50) values for phenylephrin e and vasopressin were significantly different in the aorta, but not i n the mesenteric artery, between the two groups, In contrast, octreoti de treatment did not alter the contractile responsiveness of arteries from sham-operated rats. 4. These results show that, in rats with port al vein stenosis, octreotide increases arterial contractile responsive ness and reduces portal pressure.