title: Frequency-dependent depression of ganglionic transmission by propranolol and diltiazem in the superior cervical ganglion of the guinea-pig.
abstract: 1 Effects of propranolol and diltiazem on ganglionic transmission in the superior cervical ganglion of the guinea-pig were investigated with intracellular recording techniques. 2 Propranolol and diltiazem (5 X 10(-6)-10(-5) M) induced a transmission failure in the ganglion upon preganglionic nerve stimulation at high frequency (25-30 Hz) without affecting action potentials induced by direct stimulation of the soma membrane, or potentials induced by iontophoretically applied acetylecholine. 3 The results suggest that propranolol and diltiazem may act on preganglionic nerve terminals to inhibit Ca2+ influx in a frequency-dependent manner. These agents may depress excess sympathetic activity without much affecting normal ganglionic transmission.
mesh_terms: D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D001552:Benzazepines / Q000494:pharmacology*; D004110:Diltiazem / Q000494:pharmacology*; D005260:Female; D005728:Ganglia, Sympathetic / Q000187:drug effects*; D006168:Guinea Pigs; D066298:In Vitro Techniques; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects; D008839:Microelectrodes; D011433:Propranolol / Q000494:pharmacology*; D013569:Synapses / Q000187:drug effects; D009435:Synaptic Transmission / Q000187:drug effects*
chemical_list: D001552:Benzazepines; D011433:Propranolol; D004110:Diltiazem