Transmural inhomogeneity of energy metabolism during acute global ischemia in the isolated rat heart: dependence on environmental conditions.

Cardiac energy metabolism is one of the earliest metabolic activities affected when either anoxia or ischemia are induced, as evidenced by the rapid decline of the tissue high-energy phosphate content of creatinephosphate (CrP) and ATP. Several reports deal with the spatial inhomogeneity of these changes and it is generally found, that the subendocardium is more sensitive to ischemia than the subepicardium. The metabolic transmural gradients observed during in vivo ischemia were attributed to both variations in wall tension and collateral flow. Lowe et al. recently presented evidence that in addition to these variations the higher vulnerability of the subendocardium to ischemia could be secondary to an increased metabolic rate.