Inositol phosphate responses in portal veins from portal hypertensive rats: receptor- and nonreceptor-mediated responses

Background/Aims: Venous hyporesponsiveness in portal hypertension has been reported previously by us. The present study was undertaken to investigate possible changes of phosphoinositide signal transduction pathway in the portal veins from portal hypertensive rats Methods: Portal hypertension was induced by partial portal vein ligation. Fourteen days after surgery, portal veins were removed for measurement of [3H]inositol phosphate responses to both receptor- and nonreceptor-mediated stimuli. Results: Basal [3H]inositol phosphate formation was similar between the two groups. Both phenylephrine and angiostensin II stimulated [3H]inositol phosphate formation in portal veins, but the responses were attenuated in the portal hypertensive group. In contrast, the [3H]inositol phosphate formation by nonreceptor-mediated stimuli (GTPγS, NaF/AlCl3, and phospholipase C) was similar between the two groups. Conclusions; Our results showed that the receptor-mediated [3H]inositol phosphate formation was attenuated, while the non-receptor-mediated formation was unaltered, in the portal vein from portal hypertensive rats.