Barbiturates block calcium uptake by stimulated and potassium-depolarized rat sympathetic ganglia.
The effects of two barbiturates on calcium uptake by sympathetic ganglia have been 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. Postassium-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. In sum, the data suggest that the barbiturates inhibit Ca permeability changes in both pre- and postsynaptic neurons.
D000818:Animals; D001463:Barbiturates / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism*; D002132:Calcium Radioisotopes; D003864:Depression, Chemical; D004558:Electric Stimulation; D005260:Female; D005725:Ganglia, Autonomic / Q000378:metabolism* / Q000502:physiology; D005730:Ganglionic Blockers / Q000494:pharmacology; D066298:In Vitro Techniques; D009474:Neurons / Q000378:metabolism; D011188:Potassium / Q000494:pharmacology*; D051381:Rats
D001463:Barbiturates; D002132:Calcium Radioisotopes; D005730:Ganglionic Blockers; D011188:Potassium; D002118:Calcium