On the source of the vasopressin-induced increases in diacylglycerol in hepatocytes.
In hepatocytes pre-labelled with [3H]glycerol, vasopressin increased by 20% the amount of radioactivity present in diacylglycerols. The effect of vasopressin was partially dependent on Ca2+. The magnitude of the increase in [3H]diacylglycerol was 5-times the sum of the radioactivity present in phosphatidylinositol 4-phosphate and phosphatidylinositol 4,5-bisphosphate. No stimulation by vasopressin of the initial rate of incorporation of radioactivity into diacylglycerols was observed in cells incubated in the presence of 10 mM [3H]glycerol. Treatment of hepatocytes labelled with either [3H]ethanolamine or [3H]choline with vasopressin, ionophore A23187 or phospholipase C increased the amount of radioactivity present in trichloroacetic acid extracts of the cells. The effect of vasopressin was dependent on extracellular Ca2+. It is concluded that in hepatocytes vasopressin increases diacylglycerols by a process which does not principally involve the conversion of phosphoinositides to diacylglycerol or the de novo synthesis of diacylglycerol from glycerol 3-phosphate, but does involve the Ca2+-dependent conversion of phosphatidylethanolamine and phosphatidylcholine to diacylglycerol.
D000818:Animals; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000502:physiology; D004075:Diglycerides / Q000378:metabolism*; D019856:Ethanolamine; D004983:Ethanolamines / Q000378:metabolism; D005989:Glycerides / Q000378:metabolism*; D005990:Glycerol / Q000378:metabolism; D066298:In Vitro Techniques; D050356:Lipid Metabolism; D008099:Liver / Q000378:metabolism*; D010713:Phosphatidylcholines / Q000378:metabolism; D010714:Phosphatidylethanolamines / Q000378:metabolism; D010716:Phosphatidylinositols / Q000378:metabolism; D006005:Phosphorylases / Q000378:metabolism; D010738:Type C Phospholipases / Q000378:metabolism; D014667:Vasopressins / Q000494:pharmacology*
D004075:Diglycerides; D004983:Ethanolamines; D005989:Glycerides; D010713:Phosphatidylcholines; D010714:Phosphatidylethanolamines; D010716:Phosphatidylinositols; D014667:Vasopressins; D000001:Calcimycin; D019856:Ethanolamine; D006005:Phosphorylases; D010738:Type C Phospholipases; D005990:Glycerol; D002118:Calcium