Localization and regulation by vitamin D of calcium transport proteins in rabbit cortical collecting system

An investigation of calcium transport in the rabbit kidney has identified three types of transport proteins in the distal nephron: the Na+/Ca2+ exchanger, the Ca2+-ATPase, and calbindin-D28k. Immunocytochemical studies showed that in the presence of 1alpha,25-dihydroxyvitamin D3, there was an increase in the expression of calbindin-D28 protein content, indicating a positive linear relationship between Ca2+ transport and calbindin-D28 RNA levels.