Dihydropyridine BAY-K-8644 activates chromaffin cell calcium channels.
Douglas and Rubin suggested that "the role of acetylcholine as a transmitter at the adrenal medulla is to cause some brief change in medullary cells which allows Ca ions to penetrate them and trigger the catecholamine ejection process". The Ca2+-channel blocking agents, verapamil, nifedipine and nitrendipine, have been used widely to investigate the properties of slow Ca2+ channels in a variety of tissues, including the adrenomedullary chromaffin cell. Recently, small modifications to the nifedipine molecule produced a derivative, BAY-K-8644 (methyl-1,4-dihydro-2, 6-dimethyl-3-nitro-4-(2-trifluoromethylphenyl)-pyridine-5-carboxylate), that in contrast to the Ca2+-channel blocking agents, stimulated cardiac and vascular smooth muscle contractility. We have tested whether this compound behaves as a Ca2+-channel activator at the chromaffin cell membrane as shown by Schramm et al. in smooth muscle cells. The experiments described here strongly suggest that it does so.
D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester; D000313:Adrenal Medulla / Q000187:drug effects / Q000502:physiology*; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D015220:Calcium Channels; D002415:Cats; D002417:Cattle; D002462:Cell Membrane / Q000378:metabolism; D004837:Epinephrine / Q000378:metabolism*; D007473:Ion Channels / Q000187:drug effects / Q000378:metabolism*; D009543:Nifedipine / Q000031:analogs & derivatives* / Q000378:metabolism / Q000494:pharmacology; D009568:Nitrendipine; D009638:Norepinephrine / Q000378:metabolism*; D011188:Potassium / Q000494:pharmacology; D011978:Receptors, Nicotinic / Q000378:metabolism
D002121:Calcium Channel Blockers; D015220:Calcium Channels; D007473:Ion Channels; D011978:Receptors, Nicotinic; D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester; D009568:Nitrendipine; D009543:Nifedipine; D011188:Potassium; D002118:Calcium; D009638:Norepinephrine; D004837:Epinephrine