Duodenal Active Transport of Calcium and Phosphate in Vitamin D-Deficient Rats: Effects of Nephrectomy, Cestrum diurnum, and lα,25-Dihydroxyvitamin D3

Abstract

Both the methanol:chloroform extractable material from the leaves of the Solanaceous plant, Cestrum diurnum (C.d.), and a 270 ng dose of 1.alpha., 25-dihydroxyvitamin D3 (1.alpha.,25-(OH)2D3) increased the active absorption of Ca and Pi across the proximal duodenum, studied in vitro, from sham-operated and nephrectomized (NPX) vitamin D-deficient rats. In these studies, conducted 24 h after surgery, the uremic state in the NPX animals markedly diminished the intestinal transport response to 1.alpha.,25-(OH)2D3 and lowered baseline transport values across duodenum from the NPX vitamin D-deficient controls. Both C.d. and 1.alpha., 25-(OH)2D3 elevated plasma Ca levels equally well in the sham-operated and NPX groups. The stimulation of intestinal Ca absorption in NPX animals indicates that, like the leaves of the South American plant, Solanum glaucophyllum, C.d. contains materials which can function in an analogous manner to compounds in the vitamin D group that have either a 1.alpha. hydroxyl group or its steric equivalent.