Mechanisms Involved in the Uptake of D-Glucose into the Milk-Producing Cells of Rat Mammary Tissue

There is a rapid stimulation of the rate of efflux of 3-O-methyl D-glucose from intact lactating rat mammary tissue slices in response to a change in the Na+-gradient across the basolateral plasma membrane. RNA extracted from lactating glands contains a 4 kb transcript which hybridises with the cDNA for rabbit intestinal SGLT1. A fraction of the mammary gland cells which is enriched in endoplasmic, Golgi and plasma membranes contains a protein that is immunologically similar to the Na+-dependent D-glucose symporter present in the plasma membrane of polarised epithelial cells, e.g., rabbit enterocytes, ovine enterocytes and parotid acinar cells.