[Subcellular localization of 45Ca2+ during absorption by small intestinal epithelium in rats].

Absorption of 45Ca2+ administered in to the lumen of the young rat small intestine at a concentration of 0.25 mM has been examined by electron microscopy coupled with autoradiography. 45Ca2+ has been shown to be transported through an enterocyte in the sequestered form within the membrane vesicles that detach at the base of microvilli, opening at the lateral membranes of the enterocyte, within Ca2+ being released into the intercellular space.