Direct activation by prostaglandin F2 alpha but not thromboxane A2 of glycogenolysis via an increase in inositol 1,4,5-trisphosphate in rat hepatocytes.
In rat liver prostaglandin F2 alpha (PGF2 alpha) and thromboxane A2 (TXA2), released from non-parenchymal cells, have been implicated as mediators of the enhancement of glucose and lactate output from parenchymal cells caused by sympathetic nerve stimulation [Iwai, M. et al. (1988) Eur. J. Biochem. 175, 45-50]. In isolated rat hepatocytes PGF2 alpha, of which 75% were degraded within 10 min, but not the TXA2 analogue U46619 increased inositol 1,4,5-trisphosphate (IP3), glycogen phosphorylase a activity and glucose output like noradrenaline and vasopressin; cyclic AMP remained unaltered. The maximal increase in IP3 was reached within 20 s and in phosphorylase activity as well as glucose release within 1 min. The results indicate that only PGF2 alpha but not TXA2 can play a role as a direct mediator of the sympathetic metabolic nerve actions in rat liver and that hepatocytes contain also stimulatory prostaglandin receptors linked to phospholipase C in addition to the inhibitory receptors linked to adenylate cyclase known thus far.
Athari
A
A
Universität Göttingen, Germany.
Jungermann
K
K
D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; D000818:Animals; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000378:metabolism; D015237:Dinoprost / Q000494:pharmacology*; D015544:Inositol 1,4,5-Trisphosphate; D007295:Inositol Phosphates / Q000378:metabolism*; D007700:Kinetics; D008099:Liver / Q000187:drug effects / Q000378:metabolism*; D008112:Liver Glycogen / Q000378:metabolism*; D009638:Norepinephrine / Q000494:pharmacology; D006005:Phosphorylases / Q000378:metabolism; D011450:Prostaglandin Endoperoxides, Synthetic / Q000494:pharmacology; D051381:Rats; D013403:Sugar Phosphates / Q000378:metabolism*; D013928:Thromboxane A2 / Q000494:pharmacology*; D014667:Vasopressins / Q000494:pharmacology
D007295:Inositol Phosphates; D008112:Liver Glycogen; D011450:Prostaglandin Endoperoxides, Synthetic; D013403:Sugar Phosphates; D014667:Vasopressins; D013928:Thromboxane A2; D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; D015544:Inositol 1,4,5-Trisphosphate; D015237:Dinoprost; D000242:Cyclic AMP; D006005:Phosphorylases; D009638:Norepinephrine