CALCIUM-TRANSPORT BY ISOLATED BRUSH-BORDER AND BASOLATERAL MEMBRANE-VESICLES - ROLE OF ESSENTIAL FATTY-ACID SUPPLEMENTATION

Intestinal calcium transport is important in whole body calcium homeos tasis and it is therefore of interest to understand the mechanism of a bsorption and its regulation by 1;25dihydroxyvitamin D-3 (1,25 (OH)(2) D-3) (vitamin D). Significant changes in lipid composition of membrane s have previously been shown in response to vitamin D-3 administration . Deficiency in essential fatty acids (EFAs) may influence the vitamin D-dependent calcium absorption in the intestinal tract. The purpose o f this study was to investigate the effect of unsaturated fatty acid s upplementation on calcium transport. Simultaneous measurements of calc ium transport, membrane fluidity and lipid structure have rarely been performed on the same preparation. Intestinal membrane vesicles were p repared using a novel procedure. Vesicles prepared from fish oil and e vening primrose oil supplemented animals revealed the highest calcium transport over time as well as the highest degree of unsaturation as c ompared to those from animals which were unsupplemented or given sunfl ower or coconut oil. The relative content of polyunsaturated fatty aci ds in the intestinal membranes may change fluidity, enhance calcium tr ansport and may influence the action of vitamin D-3 on calcium absorpt ion.