title: Evidence from studies employing radioactively labelled fatty acids that the stimulation of flux through the diacylglycerol pool is an early action of vasopressin on hepatocytes.
abstract: 1. In isolated hepatocytes prelabelled with [14C]-arachidonic, -stearic, -linoleic, -oleic or -palmitic acids, vasopressin increased the amount of radioactivity present in diacylglycerols. The largest increase was observed in cells labelled with arachidonic or stearic acids. 2. In cells prelabelled with [14C]- or [3H]-arachidonic acid, the onset of the increase in radioactivity in diacylglycerols induced by vasopressin was slow, the increase was partly dependent on the presence of extracellular Ca2+, and was associated with an increase in radioactivity present in phosphatidic acid which was more rapid in onset. Vasopressin decreased the amount of [3H]arachidonyl-phosphatidylinositol 4,5-bisphosphate, but the magnitude of this decrease was less than 10% of the observed increase in radioactivity in [3H]arachidonyl-diacylglycerol. 3. The concentration of vasopressin which gave half-maximal increase in [14C]arachidonyl-diacylglycerol at low extracellular Ca2+ was 10-fold higher than that which gave half-maximal stimulation of 45Ca2+ efflux. Phenylephrine, but not glucagon, also increased the amount of [14C]arachidonyl-diacylglycerol. 4. It is concluded that an early action of vasopressin on the liver cell is to increase the flux of carbon from phospholipids, including the phosphoinositides, to diacylglycerols.
mesh_terms: D000818:Animals; D016718:Arachidonic Acid; D001095:Arachidonic Acids / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D002250:Carbon Radioisotopes; D004075:Diglycerides / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D005227:Fatty Acids / Q000378:metabolism*; D005989:Glycerides / Q000378:metabolism*; D066298:In Vitro Techniques; D050356:Lipid Metabolism; D008099:Liver / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D010710:Phosphates / Q000378:metabolism; D051381:Rats; D013268:Stimulation, Chemical; D014667:Vasopressins / Q000494:pharmacology*
chemical_list: D001095:Arachidonic Acids; D002250:Carbon Radioisotopes; D004075:Diglycerides; D005227:Fatty Acids; D005989:Glycerides; D010710:Phosphates; D014667:Vasopressins; D016718:Arachidonic Acid; D002118:Calcium