Characterization of the second messengers involved in 1α,25-dihydroxyvitamin D3stimulated intestinal calcium absorption (transcaltachia)

摘要

1α,25-Dihydroxyvitamin D31α,25(OH)2D3 has been shown to generate biological responses via both genomic and nongenomic pathways. In the nongenomic process, 1α,25(OH)2D3stimulates the rapid transport of Ca2+across the chick intestinal epithelial cell, a process termed transcaltachia. In previous studies, the involvement of Ca2+-channels, protein kinase C, and cAMP-dependent kinase in the 1α,25(OH)2D3stimulated transcaltachic response have been implicated. To further characterize the elements involved in mediating the transcaltachic effect, H7, an inhibitor of protein kinase C, U73122, an inhibitor of phospholipase C, and mastoparan, an activator of G-proteins, were employed. Both H7 and U73122 suppressed 1α,25(OH)2D3stimulated intestinal Ca2+transport. Mastoparan was found to mimic the effect of 1α,25(OH)2D3to stimulate transcaltachia. Collectively, these results suggest that 1α,25(OH)2D3activations of G-proteins, phospholipase C and protein kinases are essential steps in the rapid stimulation of intestinal Ca2+tra