1. It has been reported that ortreotide partially corrects the hyperdynamic 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 hypertension. 2.
Portal hypertension was induced by partial portal vein
ligation.
Octreotide was given for 9 days subcutaneously (100 micrograms/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 pressure and plasma
glucagon concentrations compared 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 contractile responses to
phenylephrine and
vasopressin in aorta and mesenteric artery were significantly greater in the
octreotide-treated group than in the vehicle-treated group. The EC50 values for
phenylephrine and
vasopressin were significantly different in the aorta, but not in the mesenteric artery, but not in the mesenteric artery, between the two groups. In contrast,
octreotide treatment did not alter the contractile responsiveness of arteries rom
sham-operated rats. 4. These results show that, in rats with portal vein
stenosis,
octreotide increases arterial contractile responsiveness and reduces portal pressure.