Inhibitory effects of cyclopiazonic acid on the spike after-hyperpolarization in rat sympathetic neurons.
Cyclopiazonic acid (CPA), a novel specific inhibitor of Ca(2+)-ATPase in muscle sarcoplasmic reticulum, shortened the Ca(2+)-dependent after-hyperpolarization (AHP) following a spike in the rat superior cervical ganglion. This inhibitory effect was reversible and dependent on concentrations between 1 and 5 microM. The AHP in the presence of 5 microM CPA was not depressed further by ryanodine, nor was it affected by repetitive stimulation. These results suggest that CPA inhibits the intracellular Ca2+ release, probably due to the depletion of Ca2+ stores induced by inhibition of the ATP-dependent Ca2+ pump.
Ishii
Y
Y
Department of Chemical Pharmacology, Faculty of Pharmaceutical Sciences, Nagoya City University, Japan.
Kawai
T
T
Watanabe
M
M
D000818:Animals; D000252:Calcium-Transporting ATPases / Q000037:antagonists & inhibitors* / Q000187:drug effects; D066298:In Vitro Techniques; D007211:Indoles / Q000494:pharmacology*; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D013564:Sympathetic Nervous System / Q000187:drug effects*
D007211:Indoles; D000252:Calcium-Transporting ATPases; C000543:cyclopiazonic acid