Osmotically active organic solutes in the renal inner medulla

Abstract

The existence of significant amounts of non-urea organic osmolytes in the renal inner medulla has been clearly demonstrated. The principal osmolytes are glycerolphosphorylcholine, betaine, inositol, and sorbitol. Presumably they function in osmotic regulation of the inner medullary cells and may protect the cellular enzymes from the potentially harmful effects of the hypertonic extracellular environment in the inner medulla.