On the mechanism by which hormones induce the release of Ca2+ from mitochondria in the liver cell.
1. The abilities of dinitrophenol, NaCl, Ruthenium Red and the Ca2+-selective ionophore A23187 to release 45 Ca2+ from isolated hepatocytes and liver mitochondria (incubated at 37 degrees C in the presence of 0.1 microM-free Ca2+, Mg2+, ATP and phosphate ions) were compared with the action of adrenaline on 45Ca2+ release from isolated hepatocytes. The effects of adrenaline were most closely described by those of the ionophore A23187. 2. In isolated hepatocytes, a release of 45Ca2+ and stimulation of O2 utilization similar to that induced by adrenaline was observed in the presence of 500 and 20 microM-arachidonic acid respectively. The effect of arachidonic acid on 45Ca2+ release was not specific for this unsaturated fatty acid. 3. Inhibitors of arachidonic acid metabolism, including indomethacin and eicosa-5,811,14-tetraynoic acid, did not block the effects of adrenaline on 45Ca2+ or glucose release from isolated hepatocytes. 4. The ability of adrenaline to stimulate 45Ca2+ release from isolated hepatocytes was rapidly reversed after the subsequent addition of phenoxybenzamine to the cell suspension, and was completely blocked by 0.5 mM-dibucaine. 5. The results are consistent with the action of a Ca2+-selective ionophore in the mechanism by which adrenaline induces the release of Ca2+ from mitochondria in the liver cell and indicate that it is unlikely that arachidonic  acid or a metabolite of arachidonic acid is involved in this process.
D000818:Animals; D016718:Arachidonic Acid; D001095:Arachidonic Acids / Q000494:pharmacology; D001692:Biological Transport / Q000187:drug effects; D002118:Calcium / Q000378:metabolism*; D003992:Dibucaine / Q000494:pharmacology; D004837:Epinephrine / Q000494:pharmacology*; D008099:Liver / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D008930:Mitochondria, Liver / Q000187:drug effects / Q000378:metabolism*; D051381:Rats
D001095:Arachidonic Acids; D016718:Arachidonic Acid; D003992:Dibucaine; D002118:Calcium; D004837:Epinephrine