BARBITURATES BLOCK CALCIUM-UPTAKE BY STIMULATED AND POTASSIUM-DEPOLARIZED RAT SYMPATHETIC-GANGLIA

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  • 1 January 1976
    • journal article
    • research article
    • Vol. 196  (1) , 80-86
Abstract
The effects of 2 barbiturates on Ca uptake by sympathetic ganglia were examined. Sodium pentobarbital (0.4-0.75 mM) and sodium thiopental (0.3 mM) block the preganglionic stimulation-induced uptake of 45Ca by rat superior cervical ganglia but not action potential conduction in the presynaptic axons. The ganglionic-blocking agent, tetraethylammonium, does not inhibit stimulation-induced Ca uptake and does not prevent the blocking effect of thiopental. This effect is therefore probably presynaptic. K-rich media also stimulate Ca uptake by the ganglia, and this effect is markedly inhibited by pentobarbital. Since the K stimulation effect is also observed in deafferented ganglia but not in guanethidine-denervated ganglia, this effect is probably associated primarily with postsynaptic elements. The barbiturates probably inhibit Ca permeability changes in both pre- and postsynaptic neurons.