1,25 (OH) sub 2 vitamin D sub 3 -induced sup 45 Ca uptake in vascular myocytes cultured from spontaneously hypertensive and normotensive rats

The effect of 1,25 (OH){sub 2} vitamin D{sub 3} on basal {sup 45}Ca uptake was examined in vasvular smooth muscle cells cultured from mesenteric arteries of spontaneously hypertensive (SHR) and Wistar Kyoto (WKY) normotensive rats. Basal uptake of {sup 45}Ca was significantly greater in myocytes of WKY than SHR at 5, 10, 30 and 60 min incubation with the isotope. Incubation with 1 ng/ml 1,25 (OH){sub 2} vitamin D{sub 3} for 48 hr increased basal {sup 45}Ca uptake between 1-10 min in SHR and between 5-10 min in WKY. The dose-response relationship indicated that cells from both strains are equally sensitive to the calciotropic effects of 1,25 (OH){sub 2} vitamin D{sub 3} with half-maximal stimulation occurring at approximately 0.3-0.4 ng/ml. In cells of both strains maximal stimulation of {sup 45}Ca uptake was achieved only after a 12-24 hr period of incubation with hormone and pretreatment with cycloheximide inhibited 1,24 (OH){sub 2} vitamin D{sub 3}-enhanced {sup 45}Ca uptake. Although {sup 45}Ca binding by extracellular matrix material was significantly greater in WKY than SHR, 1,25 (OH){sub 2} vitamin D{sub 3} had no effect on the amount of matrix {sup 45}Ca binding in either strain.