title: Vitamin D metabolite effects on membrane potential and potassium intracellular activity in rabbit cartilage.
abstract: In rabbit cartilage growth plates, the membrane potential, Vm, and potassium intracellular activities, alpha iK, were determined in order to study the effects of long-term (48 h) and short-term (1-2 min) exposures to vitamin D metabolites. Results are as follows: (i) in proliferative cells, Vm was -55.6 +/- 0.2 mV, n = 30, and alpha ik = 50.8 +/- 4.2 mM, n = 22; (ii) in hypertrophic cells, Vm was -35.5 +/- 0.8 mV, n = 88, and alpha iK = 85.1 +/- 5.4 mM, n = 20; (iii) Vm (-44.0 +/- 1.0 mV, n = 33) and alpha iK (114.7 +/- 8.7 mM, n = 14) were increased in metatarsal hypertrophic cells incubated with 10(-10)M of 1,25(OH)2D3 but were unaffected by the presence of 24,25(OH)2D3; (iv) an hyperpolarization of Vm was observed after short-term exposure of the hypertrophic cells to 10(-10)M of 1,25(OH)2D3 (-2.2 +/- 0.2 mV, n = 34) and 24,25(OH)2D3 (-2.2 +/- 0.7 mV, n = 17) but not to 25(OH)D3 (+0.3 +/- 0.8 mV, n = 10).
mesh_terms: D015650:24,25-Dihydroxyvitamin D 3; D000818:Animals; D002117:Calcitriol / Q000494:pharmacology*; D002356:Cartilage / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D002455:Cell Division; D004100:Dihydroxycholecalciferols / Q000494:pharmacology*; D006132:Growth Plate / Q000502:physiology; D006984:Hypertrophy / Q000503:physiopathology; D066298:In Vitro Techniques; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects; D008839:Microelectrodes; D010042:Ouabain / Q000494:pharmacology; D011188:Potassium / Q000378:metabolism / Q000502:physiology*; D011817:Rabbits; D013997:Time Factors
chemical_list: D004100:Dihydroxycholecalciferols; D015650:24,25-Dihydroxyvitamin D 3; D010042:Ouabain; D002117:Calcitriol; D011188:Potassium