Determination of mitochondrial calcium content in hepatocytes by a rapid cellular fractionation technique. Vasopressin stimulates mitochondrial Ca2+ uptake.
Stimulation of hepatocytes with vasopressin (10 nM) in the presence of 1.25 mM extracellular Ca2+ increased glycogen phosphorylase activity 4-fold within 15s and provoked a rapid efflux of cell-associated Ca2+. Vasopressin also caused a transient increase in the Ca content of a mitochondria-rich fraction separated within seconds of hormone stimulation by a rapid fractionation technique [Shears & Kirk (1984) Biochem. J. 219, 375-382]. The Ca content of this fraction was restored to the control value within 2 min of hormone addition. These results indicate that mitochondria are not the source of the cell-associated Ca which is mobilized in the cytosol of vasopressin-stimulated hepatocytes. Rather, these organelles buffer the increase in cytosol [Ca2+] attributable to Ca mobilization from non-mitochondrial sources.
D000818:Animals; D002118:Calcium / Q000032:analysis / Q000378:metabolism*; D002458:Cell Fractionation / Q000379:methods; D066298:In Vitro Techniques; D008099:Liver / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D008297:Male; D008930:Mitochondria, Liver / Q000032:analysis / Q000187:drug effects / Q000378:metabolism*; D010762:Phosphorylase a / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D014667:Vasopressins / Q000494:pharmacology*
D014667:Vasopressins; D010762:Phosphorylase a; D002118:Calcium