Effects of norepinephrine on contraction and hydrolysis of phosphatidylinositols in rat aorta.
The purpose of this study was to investigate the relationship between norepinephrine-induced contraction and hydrolysis of phosphatidylinositols in rat aorta. Norepinephrine-induced contraction was associated with increased accumulation of the hydrolytic products of the phosphatidylinositols, inositol monophosphate and phosphatidic acid. Norepinephrine also induced significant decreases in phosphatidylinositol phosphate and phosphatidylinositol bisphosphate. The alpha-1 adrenoceptor antagonist, prazosin, exposure to the Ca++ channel modulator, nifedipine, and removal of extracellular Ca++ inhibited the accumulation of inositol monophosphate and contraction due to norepinephrine. These results suggest that the contraction induced by norepinephrine may be mediated by processes associated with hydrolysis of phosphatidylinositols. The hydrolysis may occur through Ca++-dependent activation of phospholipase C by alpha-1 adrenoceptor agonists.
D000818:Animals; D001013:Aorta, Thoracic / Q000502:physiology; D002118:Calcium / Q000494:pharmacology; D006868:Hydrolysis; D007295:Inositol Phosphates / Q000378:metabolism; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects*; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000502:physiology*; D009543:Nifedipine / Q000494:pharmacology; D009638:Norepinephrine / Q000494:pharmacology*; D010712:Phosphatidic Acids / Q000378:metabolism; D010716:Phosphatidylinositols / Q000378:metabolism*; D011224:Prazosin / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains
D007295:Inositol Phosphates; D010712:Phosphatidic Acids; D010716:Phosphatidylinositols; D009543:Nifedipine; D002118:Calcium; D009638:Norepinephrine; D011224:Prazosin