The role of H+ in temporary hypoxic contractility failure: different effects of pH on the force decay and on the force recovery after reoxygenation.
The contractility of isolated ventricle strips of the frog heart (Rana pipiens) was studied under temporary N2 hypoxia and during subsequent recovery after reoxygenation under different extracellular H ion concentrations (pH 6.0-8.5). The recovery of contractile force was three times more pH-sensitive than force decay. Under slow pacing (12/min) at +12 degrees C there was almost complete recovery to control values within 60 min at pHe above 7.0. Under this pH level recovery was largely delayed (pH 6.5) or did not occur (pH 6.0). Prolongation of contraction during the reoxygenation phase, observed at low H ion concentrations, was largely delayed or absent under high concentrations of H ions.
The role of H+ in temporary hypoxic contractility failure: different effects of pH on the force decay and on the force recovery after reoxygenation. The contractility of isolated ventricle strips of the frog heart (Rana pipiens) was studied under temporary N2 hypoxia and during subsequent recovery after reoxygenation under different extracellular H ion concentrations (pH 6.0-8.5). The recovery of contractile force was three times more pH-sensitive than force decay. Under slow pacing (12/min) at +12 degrees C there was almost complete recovery to control values within 60 min at pHe above 7.0. Under this pH level recovery was largely delayed (pH 6.5) or did not occur (pH 6.0). Prolongation of contraction during the reoxygenation phase, observed at low H ion concentrations, was largely delayed or absent under high concentrations of H ions.