[Changes in cytosol Ca(2+)-, Mg(2+)-, H(+)-, N(+)-, and K(+)-concentrations in cultivated hepatocytes in hypoxic conditions].

AIM

It is assumed that disturbances of cellular ion homeostasis, especially an increase in the cytosolic Ca2+ concentration, are of decisive importance for hypoxic cell injury. The aim of this study is the determination of alterations in the cytosolic Ca2+, Mg2+, H+, Na+ and K+ concentration in cultured hepatocytes during hypoxia.

METHODS

The alterations of ion homeostasis under hypoxic conditions were studied in primary cultures of isolated rat hepatocytes by using fluorescence microscopy.

RESULTS

The measurements of cytosolic Ca2+ concentration showed no alterations during the first 3-4 h of hypoxia. About 1-2 h before cell injury became evident Ca2+ increased from 147 +/- 28 to 385 +/- 31 nM. Similarly the cytosolic Mg2+ concentration increased from 0.63 +/- 0.05 to 1.42 +/- 0.11 mM in a late stage of hypoxia. In contrast, the cytosolic Na+ concentration increased continuously from 16 +/- 2 mM at start to 76 +/- 9 mM after 5 h of hypoxic conditions. The cytosolic K+ concentration remained constant for 2 h (129 +/- 7 mM) but then decreased down to 31 +/- 18 mM. The intracellular H+ concentration increased slightly under hypoxic conditions, the pH decreased from 7.35 +/- 0.02 to 7.19 +/- 0.04.

CONCLUSION

The results indicate that cytosolic Ca2+ plays only a minor role in the pathomechanism of hypoxic hepatocellular injury but suggest an important role of the cytosolic Na+ concentration in this process.