Norepinephrine Stimulation of Phosphoinositide Hydrolysis in Rat Cerebral Cortex Is Associated with the Alpha1-Adrenoceptor |
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Authors: | Darryle D Schoepp Sheila M Knepper Charles O Rutledge |
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Institution: | M.R.C. Neurochemical Pharmacology Unit, Medical Research Council Centre, Cambridge;Department of Parasitology, University of Cambridge, Cambridge, U.K. |
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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. |
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Keywords: | Neurotensin Endo-oligopeptidases A and B Rabbit b14grain |
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