Depressed duodenal calcium absorption in the diabetic rat: restoration by Solanum malacoxylon.

Duodenal calcium absorption is depressed in alloxan and streptozotocin diabetic rats taking normal amounts to dietary vitamin D. Depression of absorption appears to be at least in part the result of altered metabolism of vitamin D with failure to form 1,25-dihydroxycholecalciferol (1,25-(OH)2D3), the vitamin D metabolite that acts directly on duodenum to stimulate calcium absorption. The South American plant Solanum malacoxylon causes extensive soft tissue calcification when ingested by cattle. An extract of this plant restores calcium absorption depressed by dietary strontium blockage of 1,25-(OH)2D3 formation in chicks. We gave an aqueous extract of S. malacoxylon to diabetic rats and restored duodenal calcium absorption to normal. These findings provide further evidence of the ability of a factor in the S. malacoxylon extract to mimic the actions of 1,25-(OH)2D3 on duodenal calcium transport and reinforce the hypothesis that abnormal vitamin D metabolism is an important determinant of depressed duodenal calcium absorption in diabetes.