EXPRESSION OF PHOTORECEPTOR CYCLIC NUCLEOTIDE-GATED CATION CHANNEL ALPHA-SUBUNIT (CNGC-ALPHA) IN THE LIVER AND SKELETAL-MUSCLE

Glucagon and beta-adrenergic agents increase cAMP levels and stimulate Ca2+ influx in liver cells, There is no consensus as to the mechanism by which these hormones stimulate the influx of Ca2+. Using mouse ret inal rod CNGC alpha cDNA probes, we cloned rat liver and skeletal musc le, and human hepatic CNGC alpha subunit sequences showing 97-100% ide ntity with the human rod channel, In order to assess channel activity, the effect of cyclic nucleotides on free intracellular Ca2+ levels of isolated hepatocytes was measured, Dibutyryl-cAMP was more effective in increasing free Ca2+ levels than dibutyryl-cGMP. These data indicat e that the CNGC alpha subunit is expressed in the both liver and skele tal muscle possibly mediating hormonal effects on ion fluxes.