Chronic renal failure increases cytosolic Ca2+ of hepatocytes.

Chronic renal failure (CRF) is associated with increased Ca2+ content of liver and reduced hepatic lipase activity. This has been attributed to a rise in cytosolic Ca2+ ([Ca2+]i) of the hepatocytes, but data on this issue are lacking. We examined the [Ca2+]i and ATP content of hepatocytes as well as the activity of Na(+)-K(+)-adenosinetriphosphatase (Na(+)-K(+)-ATPase), Ca(2+)-ATPase, and Na+/Ca2+ exchanger of hepatic membrane vesicles from normal rats, animals with 6 wk of CRF, CRF normocalcemic parathyroidectomized (CRF-PTX) rats, and CRF and normal animals treated with verapamil (CRF-V, normal-V). [Ca2+]i in hepatocytes of CRF rats was higher (281 +/- 7.4 nM) and ATP lower (6.4 +/- 1.8 nmol/mg protein) than in normal (209 +/- 5.3 nM; 12.5 +/- 0.89 nmol/mg protein), CRF-PTX (212 +/- 1.0 nM; 13.7 +/- 0.79 nmol/mg protein), normal-V (215 +/- 2.3 nM; 14.2 +/- 0.77 nmol/mg protein), and CRF-V rats (209 +/- 7.4 nM; 14.8 +/- 0.72 nmol/10(6) cells). The Na(+)-K(+)-ATPase, the maximal velocity of Ca(2+)-ATPase, and the activity of the Na+/Ca2+ exchanger were reduced, whereas the Michaelis constant of Ca(2+)-ATPase was increase in CRF rats compared with the other four groups of rats. The values in the latter groups were not different.(ABSTRACT TRUNCATED AT 250 WORDS)