Increased formation of phosphatidic acid induced with vasopressin or Ca2+ ionophore A23187 in rat hepatocytes.
The effects of vasopressin and Ca2+ ionophore A23187 on phospholipid metabolism were investigated in rat hepatocytes. Vasopressin stimulated the incorporation of [32P]Pi into phosphatidic acid within 2 min but then it returned to control level after 10 min. On the other hand, the stimulation of the incorporation of [32P]Pi into phosphatidylinositol continued with incubation times up to 20 min. The Ca2+ ionophore A23187 also increased the 32P-labeling in phosphatidic acid, although it had no effect on [32P]Pi incorporation into phosphatidylinositol. Concerning the incorporation of [3H]glycerol, vasopressin did not enhance its incorporation into phosphatidic acid and phosphatidylinositol. The Ca2+ ionophore A23187 increased the incorporation into phosphatidic acid without significant effects on that into phosphatidylinositol. In the hepatocytes prelabeled with [3H]arachidonic acid, stimulated degradation of phosphatidylinositol with the addition of vasopressin and resultant formation of phosphatidic acid were observed within 5 min. The transient accumulation of diacylglycerol, the product of phosphatidylinositol hydrolysis, also occurred within 5 min with vasopressin. On the other hand, with the Ca2+ inophore A23187, stimulated degradation of triacylglycerol to diacylglycerol and the consequent formation of phosphatidic acid were observed. The Ca2+ ionophore A23187 caused a significant release of free [3H]arachidonic acid, although vasopressin had no effect.
D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D016718:Arachidonic Acid; D001095:Arachidonic Acids / Q000378:metabolism; D000001:Calcimycin / Q000494:pharmacology*; D005990:Glycerol / Q000378:metabolism; D066298:In Vitro Techniques; D008099:Liver / Q000378:metabolism*; D010712:Phosphatidic Acids / Q000096:biosynthesis*; D010716:Phosphatidylinositols / Q000378:metabolism; D010743:Phospholipids / Q000378:metabolism; D051381:Rats; D013997:Time Factors; D014667:Vasopressins / Q000378:metabolism*
D000900:Anti-Bacterial Agents; D001095:Arachidonic Acids; D010712:Phosphatidic Acids; D010716:Phosphatidylinositols; D010743:Phospholipids; D014667:Vasopressins; D016718:Arachidonic Acid; D000001:Calcimycin; D005990:Glycerol