The matching of energy supply and demand under hypoxic conditions is critical for sustaining myocardial function. Numerous reports indicate that basal energy requirements and ion handling may differ between the ventricles. We hypothesized that ventricular response to
hypoxia shows interventricular differences caused by the heterogeneity in
glucose metabolism and expression and activity of ion transporters. Thus we assessed
glucose utilization rate,
ATP,
sodium and
potassium concentrations, Na, K-
ATPase activity, and tissue reduced:
oxidized glutathione (GSH/
GSSG) content in the right and left ventricles before and after the exposure of either the whole animals or isolated blood-perfused hearts to
hypoxia. The
hypoxia-induced boost in
glucose utilization was more pronounced in the left ventricle compared with the right one.
ATP levels in the right ventricle of hypoxic heart were lower than those in the left ventricle. Left ventricular
sodium content was higher, and hydrolytic Na, K-
ATPase activity was reduced compared with the right ventricle. Administration of the Na, K-
ATPase blocker
ouabain caused rapid increase in the right ventricular Na(+) and elimination of the interventricular Na(+) gradients. Exposure of the hearts to
hypoxia made the interventricular heterogeneity in the Na(+) distribution even more pronounced. Furthermore, systemic
hypoxia caused oxidative stress that was more pronounced in the right ventricle as revealed by GSH/
GSSG ratios. On the basis of these findings, we suggest that the right ventricle is more prone to hypoxic damage, as it is less efficient in recruiting
glucose as an alternative fuel and is particularly dependent on the efficient Na, K-
ATPase function.