Effects of 1alpha,25-dihydroxyvitamin D3 and Solanum glaucophyllum on intestinal calcium and phosphate transport and on plasma Ca, Mg and P levels in the rat.
The responses elicited by a single dose of either S. glaucophyllum (SG) or 1alpha,25-dihydroxyvitamin D3 (1alpha, 25-(OH)2D3) in vitamin D-deficient rats were qualitatively identical. Both compounds stimulated duodenal absorption of calcium and phosphate 3 h after administration, and the effects persisted for 96 h. The SG effects on calcium transport were maximal at 6 h and exceeded the greatest response to 1alpha,25-(OH)2D3 which occurred at 48 h. While the early SG effects on phosphate absorption exceeded those of 1alpha,25-(OH)2D3, the latter compound had a much greater effect at 48 h. Both SG and 1alpha, 25-(OH)2D3 produced marked hyperphosphatemia that was accompanied by hypocalcemia and transient hypermagnesemia at 3-6 h. The phosphatemia increased for 48 h in the 1alpha,25-(OH)2D3 group and fell toward baseline between 48 and 96 h, while this parameter was maximal in the SG group at 3-12 h and returned to baseline values by 96 h. Plasma calcium levels tended to vary inversely with phosphorus concentrations and did not exceed baseline values until 48 h for the SG group and 96 h for the 1alpha,25-(OH)2D3 group. We suggest that the hypocalcemia is due to calcium phosphate precipitation. The quantitative differences in the effects on calcium and phosphorus metabolism may be dose-related. The responses to SG suggest that a gram of dried leaf has approximately the same activity as 1 mug of 1alpha,25-(OH)2D3. It appears that the water-soluble SG factor has the same biological effects on Ca and P metabolism as does 1alpha,25-(OH)2D3.
D000818:Animals; D001693:Biological Transport, Active / Q000187:drug effects; D002118:Calcium / Q000097:blood / Q000378:metabolism*; D002130:Calcium Phosphates / Q000378:metabolism; D004100:Dihydroxycholecalciferols / Q000008:administration & dosage / Q000494:pharmacology*; D004386:Duodenum / Q000187:drug effects / Q000378:metabolism; D006887:Hydroxycholecalciferols / Q000494:pharmacology*; D007413:Intestinal Mucosa / Q000378:metabolism*; D008274:Magnesium / Q000097:blood; D008297:Male; D010710:Phosphates / Q000097:blood / Q000378:metabolism*; D010936:Plant Extracts / Q000494:pharmacology*; D051381:Rats
D002130:Calcium Phosphates; D004100:Dihydroxycholecalciferols; D006887:Hydroxycholecalciferols; D010710:Phosphates; D010936:Plant Extracts; D008274:Magnesium; D002118:Calcium