1,25-Dihydroxyvitamin D3 control of free cytosolic Ca2+ in the kidney

Summary Changes in cytosolic calcium (Ca]i) have been implicated in the regulation of various cellular processes. 1,25-dihydroxyvitamin D₃ (1,25 (OH)₂D₃) has been reported to increase Ca]i in hepatocytes, Hl-60, parathyroid cells and osteoblasts. It is not clear, however, whether or not 1,25 (OH)₂D₃ increases Ca]i in their another important target cells, renal cells. In order to adress this issue, the effect of 1,25 (OH)₂D₃ on Ca]i was examined in a newly established mouse renal cortical slice perifusion system using a fluorescent Ca²⁺ indicator, fura-2. 1,25 (OH)₂D₃ at physiological concentrations increased Ca]i within 2 min in a dose-dependent manner both in the presence and absence of extracellular Ca²⁺. 24,25 (OH)₂D₃ even at 10⁻⁷M did not affect Ca]i levels. These results demonstrated that 1,25 (OH)₂D₃ very rapidly increased Ca]i in another target cells, renal cells and our newly established mouse renal perifusion system may be useful to study the effects of vitamin D metabolites on Ca]i in renal cells. This study was supported in part by a grant-in-aid from the Ministry of Education, Science, and Culture and the Ministry of Health and Welfare, Japan.