Effects of vasopressin on phosphoinositides and prostaglandin production in cultured mesangial cells

We studied the effects of vasopressin on phospholipid metabolism in mesangial cells and the temporal relationship of these changes to prostaglandin production. The changes included: 1) increased breakdown of phosphatidylinositol (PI), 2) increased breakdown of diphosphoinositide (PI-P) and triphosphoinositide (PI-P₂), 3) an increase in the mass of diglyceride and phosphatidic acid, 4) increased synthesis, first of PI-P and PI-P₂, then phosphatidic acid, and, finally, PI, and 5) increased water-soluble inositol phosphates. Vasopressin treatment resulted in a significant increase (90%) in the mass of phosphatidic acid and a smaller (13%) decline in the mass of PI. Changes in diglyceride were seen following 45 s of treatment with vasopressin. Alterations of phosphoinositide metabolism were seen as early as 45 s and continued for up to 5 h following hormone exposure. By contrast, prostaglandin production declined after 30 min. These observations on vasopressin-stimulated metabolism in cultured mesangial cells may provide a basis for an understanding of the functional changes that follow hormone exposure.