title: Norepinephrine stimulation of phosphoinositide hydrolysis in rat cerebral cortex is associated with the alpha1-adrenoceptor.
abstract: Norepinephrine (NE) and the selective alpha1-adrenoceptor agonist phenylephrine (PE) both markedly stimulate the formation of [3H]inositol phosphates in a concentration-dependent manner upon incubation with [3H]myo-inositol. The selective alpha2 agonist, clonidine, did not significantly alter [3H]inositol phosphate formation, even at concentrations as high as 10(-3) M. The alpha1 antagonist prazosin (IC50, 0.036 microM) was 300 times more potent than the alpha2 antagonist yohimbine (IC50, 10.7 microM) as an inhibitor of NE (10(-4) M)-stimulated phosphatidylinositol (PI) hydrolysis. These results indicate that the alpha1-, but not the alpha2-adrenoceptor subtype in rat brain is coupled to phosphoinositide hydrolysis.
mesh_terms: D000818:Animals; D002540:Cerebral Cortex / Q000187:drug effects / Q000378:metabolism*; D003000:Clonidine / Q000494:pharmacology; D006868:Hydrolysis; D007545:Isoproterenol / Q000494:pharmacology; D008297:Male; D009638:Norepinephrine / Q000494:pharmacology*; D010656:Phenylephrine / Q000494:pharmacology; D010716:Phosphatidylinositols / Q000378:metabolism*; D011224:Prazosin / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D011942:Receptors, Adrenergic, alpha / Q000502:physiology*; D015016:Yohimbine / Q000494:pharmacology
chemical_list: D010716:Phosphatidylinositols; D011942:Receptors, Adrenergic, alpha; D010656:Phenylephrine; D015016:Yohimbine; D007545:Isoproterenol; D003000:Clonidine; D009638:Norepinephrine; D011224:Prazosin