BAY K 8644-induced oscillations in rabbit gall-bladder transepithelial potential difference.
The effects of the Ca2+-channel activator BAY K 8644 (a novel dihydropyridine) on transepithelial potential difference (Pd), electrical resistance (Rt), and unidirectional Na+-fluxes were studied in the rabbit gall-bladder. It was observed that BAY K 8644 at concentrations between 10(-7) and 10(-5) M induced regular oscillations in the transepithelial Pd, without affecting the mean value of Pd (or Rt). The mean oscillatory frequency was 18 mHz (approximately 1 cycle per min), and the mean amplitude was 30-35 microV. Oscillations were predominantly elicited from the serosal side. 10(-5) M BAY K 8644 reduced net Na+ -absorption by 16% by inhibiting the mucosa-to-serosa flux. Nifedipine blocked the Pd-oscillations but did not reverse the Na+-transport inhibition. The observed effects of BAY K 8644 are consistent with activation of Ca2+-channels and an increase in intracellular Ca2+-concentration.
D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester; D000818:Animals; D004553:Electric Conductivity; D004848:Epithelium / Q000187:drug effects / Q000378:metabolism / Q000502:physiology; D005260:Female; D005704:Gallbladder / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D066298:In Vitro Techniques; D009543:Nifedipine / Q000031:analogs & derivatives* / Q000494:pharmacology; D011817:Rabbits; D012964:Sodium / Q000378:metabolism
D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester; D012964:Sodium; D009543:Nifedipine