The Effects of Hydroxylated Derivatives of Vitamin D3 and of Extracts of Solanum Malacoxylon on the Absorption of Calcium, Phosphate and Water from the Jejunum of Pigs

Abstract

The prolonged ingestion by cattle of the leaves of the plant Solanum malacoxylon (SM) causes massive soft tissue calcification of large blood vessels, heart, lungs and tendons. There is also marked erosion of cartilage of the appendicular skeleton. This condition, known in the Argentine as “enteque seco”, can be a cause of considerable economic loss (10). It has been shown with rabbits that the oral or subcutaneous administration of an aqueous extract of SM leaves increases plasma concentration of calcium and inorganic phosphate (5). These effects were shown to result from increased absorption of calcium and phosphate from the digestive tract and raised bone resorption rate. They were similar to those observed following vitamin D administration, but quicker in both onset and decay. The stimulatory effect of SM leaves on dietary calcium absorption has also been clearly shown in cattle (6). Using embryonic chick intestine, Corradino (1) has demonstrated that vitamin D3 and also its metabolites 25-hydroxycholecalciferol (25-HCC) and 1,25-dihydroxycholecalciferol (1,25-DHCC) stimulate the synthesis of intestinal calcium-binding protein and enhance the uptake of labelled calcium. Similarly, using both intact and anephric rats, it has been shown that the synthetic analogue of 1,25-DHCC, lα-hydroxy vitamin D3 (lα-HCC), increases intestinal calcium transport with a potency similar to 1,25-DHCC on a weight basis (4).