alpha-Adrenergic receptor-mediated depolarization of rat neocortical astrocytes in primary culture.

The membrane potentials of rat neocortical astrocytes growing in primary cultures (mean resting potential; -79 mV at [K+]o = 4.5 mM) were depolarized by up to 30 mV by 10(-5) M norepinephrine added to the medium, or up to 11 mV by norepinephrine or phenylephrine applied by ionophoresis. This depolarization could be inhibited by the alpha-adrenergic receptor antagonist phentolamine (10(-5) M) but not by the beta-adrenergic antagonist propranolol (10(-5) M). These results suggest that the norepinephrine-evoked depolarizations seen in these cells may be mediated through an alpha-adrenergic receptor.