Electron Microscopic Study of the Inner Medulla in Rat Kidneys under Conditions of Vasopressin Treatment Combined with Prostaglandin Synthesis Blockade.

Ultrastructural changes in cells of the renal inner medulla involved in the realization of the antidiuretic effect of vasopressin under conditions of prostaglandin synthesis blockade were studied in the kidneys of Wistar rats and endogenous vasopressin-deficient homozygous Brattleboro rats. The results indicated uniform trend to an increase in the number of clathrincoated vesicles under conditions of hormone treatment combined with prostaglandin synthesis blockade in animals with different neurohypophyseal status. These changes reflected translocation of aquaporins and an increase in the permeability of the collecting tubular epithelium for water. Brattleboro rats, but not Wistar rats, exhibited ultrastructural signs of synthesis activation in the epithelium and widening of the intercellular gaps, which could indicate more intense paracellular water transport.