Genome-independent effects of 1,25-dihydroxy vitamin D-3 on membrane potential.

Cell membrane potential, Vm, was monitored in rabbit hypertrophic cartilage metatarsals, amphibian proximal tubule and muscle cells during application of 1,25-dihydroxy vitamin D-3, 25-hydroxy vitamin D-3 or cholesterol (10(-10) M). 1,25-Dihydroxy vitamin D-3 elicited quick variations of Vm (in less than 1 min) in proximal tubular cells (whether injected in the lumen or in peritubular capillaries) and in cartilage. The precursor 25-hydroxy vitamin D-3 and cholesterol produced a small shift of Vm in proximal tubule only when applied from the luminal side, but this change was significantly smaller than that observed with 1,25-dihydroxy vitamin D-3. Muscle cells were unresponsive to both metabolites and cholesterol. It is concluded that rapid effects of 1,25-dihydroxy vitamin D-3 on Vm, in target cells, are specific, most likely due to permeability changes and not related to nuclear protein synthesis; they may contribute to early modulation of cell function.