title: K(+)-evoked depolarization stimulates cyclic AMP accumulation in photoreceptor-enriched retinal cell cultures: role of calcium influx through dihydropyridine-sensitive calcium channels.
abstract: The effect of membrane depolarization on cyclic AMP synthesis was studied in glia-free, low-density, monolayer cultures of chick retinal photoreceptors and neurons. In photoreceptor-enriched cultures prepared from embryonic day 6 retinas and cultured for 6 days, elevated K+ concentrations increased the intracellular concentration of cyclic AMP and stimulated the conversion of [3H]adenine to [3H]cyclic AMP. The K(+)-evoked increase of cyclic AMP accumulation was blocked by omitting CaCl2 from the incubation medium, indicating a requirement for extracellular Ca2+. Stimulation of cyclic AMP accumulation was also inhibited by nifedipine, methoxyverapamil, Cd2+, Co2+, and Mg2+, and was enhanced by the dihydropyridine Ca2+ channel agonist Bay K 8644. The enhancement of K(+)-evoked cyclic AMP accumulation by Bay K 8644 was antagonized by nifedipine. Thus, Ca2+ influx through dihydropyridine-sensitive channel is required for depolarization-evoked stimulation of cyclic AMP accumulation in photoreceptor-enriched cultures.
authors.affiliation: Department of Pharmacology, Emory University School of Medicine, Atlanta, Georgia 30322.
authors.forename: P M
authors.initials: PM
authors.lastname: Iuvone
authors.forename: J
authors.initials: J
authors.lastname: Gan
authors.forename: G
authors.initials: G
authors.lastname: Avendano
mesh_terms: D015056:1-Methyl-3-isobutylxanthine / Q000494:pharmacology; D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester / Q000494:pharmacology; D012368:4-(3-Butoxy-4-methoxybenzyl)-2-imidazolidinone / Q000494:pharmacology; D000818:Animals; D002104:Cadmium / Q000494:pharmacology; D019256:Cadmium Chloride; D002118:Calcium / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D015220:Calcium Channels / Q000187:drug effects / Q000378:metabolism*; D002478:Cells, Cultured; D002642:Chick Embryo; D003035:Cobalt / Q000494:pharmacology; D000242:Cyclic AMP / Q000378:metabolism*; D007700:Kinetics; D015636:Magnesium Chloride / Q000494:pharmacology; D008564:Membrane Potentials / Q000187:drug effects; D009543:Nifedipine / Q000494:pharmacology*; D010786:Photoreceptor Cells / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D011188:Potassium / Q000494:pharmacology*; D012160:Retina / Q000502:physiology*; D012165:Retinal Ganglion Cells / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*
chemical_list: D002121:Calcium Channel Blockers; D015220:Calcium Channels; D002104:Cadmium; D015636:Magnesium Chloride; D012368:4-(3-Butoxy-4-methoxybenzyl)-2-imidazolidinone; D003035:Cobalt; D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester; D000242:Cyclic AMP; C018021:cobaltous chloride; D009543:Nifedipine; D019256:Cadmium Chloride; D011188:Potassium; D002118:Calcium; D015056:1-Methyl-3-isobutylxanthine