Evidence for the existence of alpha- and beta-adrenoceptors on cultured glial cells--an electrophysiological study.
The action of adrenergic alpha- and beta-agonists and antagonists has been studied on the membrane potential and resistance of glial cells of cultured rat central nervous system. Noradrenaline and the alpha-adrenoceptor stimulating agents phenylephrine and clonidine (10(-7) to 10(-4)M) depolarized the glial membrane, whereas the beta-agonist isoprenaline caused a hyperpolarization at low concentrations (10(-7) and 10(-6)M). The effects of noradrenaline and phenylephrine were reversibly blocked by the alpha-antagonist phentolamine, whereas those of isoprenaline were antagonized by the beta-blocker atenolol. Atenolol did not affect the depolarization by noradrenaline. The glial depolarization induced by the alpha-agonists was not the consequence of a change in the extracellular K+-concentration unlike that produced by amino acid transmitters. The present results, together with those of biochemical and autoradiographic binding studies, suggest that alpha- and beta-adrenoceptors occur on glial cells and that the glial depolarization is mediated by alpha-receptors, whereas the hyperpolarization is due to activation of beta-receptors.
D000818:Animals; D001253:Astrocytes / Q000032:analysis* / Q000378:metabolism; D003000:Clonidine / Q000494:pharmacology; D046508:Culture Techniques; D004594:Electrophysiology; D007545:Isoproterenol / Q000494:pharmacology; D009638:Norepinephrine / Q000494:pharmacology; D010656:Phenylephrine / Q000494:pharmacology; D011188:Potassium / Q000378:metabolism; D051381:Rats; D011941:Receptors, Adrenergic / Q000032:analysis* / Q000033:anatomy & histology*; D011942:Receptors, Adrenergic, alpha / Q000032:analysis*; D011943:Receptors, Adrenergic, beta / Q000033:anatomy & histology*
D011941:Receptors, Adrenergic; D011942:Receptors, Adrenergic, alpha; D011943:Receptors, Adrenergic, beta; D010656:Phenylephrine; D007545:Isoproterenol; D003000:Clonidine; D011188:Potassium; D009638:Norepinephrine