title: Effects of Ca antagonists on the action potential and their relationship to the muscarinic ACh actions in isolated sympathetic neurons of rabbits.
abstract: Muscarinically induced depressions of the shoulder in the falling phase as well as the after-spike-hyperpolarization and -depolarization of the action potential in the isolated sympathetic neurons of rabbits were mimicked by a novel peptide Ca channel blocker, omega-conotoxin (synthetic; 0.1-0.5 microM). Cobalt ions (0.1-2 mM) showed bidirectional effects on the shoulder, an early depression followed by a later prolongation, while they consistently induced depressions of other components. Organic Ca channel blockers, verapamil and D-600 (1-50 microM) and nifedipine (0.1-1 microM) appeared to have other effects as they rather caused a prolongation of the falling phase that was shortened by further application of acetylcholine.
mesh_terms: D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D002478:Cells, Cultured; D003035:Cobalt / Q000494:pharmacology; D005711:Gallopamil / Q000494:pharmacology; D005728:Ganglia, Sympathetic / Q000187:drug effects*; D008297:Male; D008978:Mollusk Venoms / Q000494:pharmacology; D009543:Nifedipine / Q000494:pharmacology; D011817:Rabbits; D011976:Receptors, Muscarinic / Q000187:drug effects*; D014700:Verapamil / Q000494:pharmacology; D020866:omega-Conotoxin GVIA
chemical_list: D002121:Calcium Channel Blockers; D008978:Mollusk Venoms; D011976:Receptors, Muscarinic; D005711:Gallopamil; D003035:Cobalt; D020866:omega-Conotoxin GVIA; D014700:Verapamil; D009543:Nifedipine