CA2-CELLS( CALMODULIN EFFECTS ON CAMP RESPONSE IN CULTURED CHICK CILIARY EPITHELIAL)

The authors investigated the influence of the elevation of intracellul ar Ca2+ concentration on the production of cyclic adenosine 3',5'-mono phosphate (cAMP) using cultured chick embryo ciliary epithelium (CE). We examined the effects of calcium ionophore (A23187) on cAMP producti on after incubation with vasoactive intestinal peptide (VIP), isoprote renol (ISO), sodium fluoride (NaF) or forskolin (FSK). A23187 had no e ffect on the basal cAMP level, or the NaF- and FSK-stimulated response s for cAMP level; but A23187 potentiated VIP- and ISO-stimulated cAMP responses. Calmodulin antagonist (W-7) was very effective in inhibitin g the potentiating effects of A23187 on VIP- and ISO-stimulated produc tion of cAMP. Our present findings suggested that Ca2+/calmodulin may potentiate the receptor-mediated cAMP pathway through Ca2+/calmodulin- dependent protein kinase in the CE.