"Stimulation of dihydropyridine-sensitive Ca2+ influx in cultured myoblasts by 1,25(OH)2-vitamin D3".

The rapid, non-genomic effects of 1,25(OH)2-vitamin D3 [1,25(OH)2D3] on calcium influx in cultured neonate rat and embryonic chick myoblasts were investigated. The hormone stimulated 45Ca uptake in a time (1-10 min) and dose (10(-11)-10(-7) M)-dependent manner. The effects of 1,25(OH)2D3 on both rat and chick myoblasts were mimicked by the Ca(2+)-channel agonist BAY K8644 and effectively suppressed by the antagonist nifedipine. 1,25(OH)2D3 induction of Ca2+ uptake was dependent on the presence of extracellular calcium, since it was abolished by prior addition of EGTA and was restored upon the addition of 1 mM Ca2+ Cell membrane depolarization with high K+, similarly to the hormone, elicited a rapid increase in Ca2+ uptake (+75% above control). These results suggest the modulation of Ca2+ influx through competent calcium channels in rat and chick embryo myoblasts by 1,25(OH)2D3.