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Heterogeneity of intracellular potassium activity and membrane potential in hypoxic guinea pig ventricle.
- Source :
-
Circulation research [Circ Res] 1981 Nov; Vol. 49 (5), pp. 1181-9. - Publication Year :
- 1981
-
Abstract
- The relationship between membrane potential (Em) and the potassium equilibrium potential (EK) was investigated in hypoxic guinea pig papillary muscle. After more than 8 hours of hypoxia, cells with near normal Em (-86.2 +/- 0.9 mV) and action potentials were observed. However, the intracellular potassium concentration ([K+]i) based on chemical analysis and the assumption that potassium was homogeneously distributed was 41.8 +/- 4.3 mM; the apparent EK was -55.7 +/- 2.9 mV, significantly positive to Em. Measurements with potassium ion-selective microelectrodes revealed that prolonged hypoxia results in at least two populations of cells with different characteristics. The first population had an intracellular potassium activity (aiK) of 101.5 +/- 1.9 mM, and EK was 4.7 mV negative to Em. In contrast, EK was 33.4 +/- 1.3 mV negative to Em in the second population. These cells also exhibited a reduced sensitivity to changes in bath potassium, and calculations suggest aiK was about 18 mM. The existence of cell populations with a near normal and very low aiK can explain the intermediate value of [K+]i calculated assuming a homogenous potassium distribution. Cells with near normal Em and action potentials represent the population with near normal aiK. Hypoxia may also cause non-uniform changes in other cellular characteristics.
Details
- Language :
- English
- ISSN :
- 0009-7330
- Volume :
- 49
- Issue :
- 5
- Database :
- MEDLINE
- Journal :
- Circulation research
- Publication Type :
- Academic Journal
- Accession number :
- 7296784
- Full Text :
- https://doi.org/10.1161/01.res.49.5.1181