High energy
phosphate levels are depressed following global
ischemia and require several days to completely recover. Short-term methods to enhance
ATP recovery have included infusion of
ATP precursors, inhibition of
enzymes that catabolize
AMP, and membrane transport stabilization. Several precursors have been used to augment
adenine nucleotide synthesis including
adenosine,
inosine,
adenine, and
ribose. Because of the short-term nature of previous experiments, recovery had been incomplete and the effects in the intact animal unknown. The purpose of this study was to determine the effects of
ribose infusion in a long-term model of global
ischemia and attempt to identify the precursor which limits myocardial
ATP regeneration in the intact animal. Global
myocardial ischemia (20 min, 37 degrees C) was produced in dogs on
cardiopulmonary bypass. With reperfusion either
ribose (80 mM) in
normal saline or
normal saline alone was infused at 1 ml/min into the right atrium and the animals were followed for 24 hr. Ventricular biopsies were obtained through an indwelling ventricular
cannula prior to
ischemia, at the end of
ischemia, and 4 and 24 hr postischemia and analyzed for
adenine nucleotides and
creatine phosphate levels. Radiolabeled
microspheres were used to measure myocardial and renal blood flows and no significant difference was found between
ribose-treated control groups. In both groups, myocardial
ATP levels fell by at least 50% at the end of
ischemia. No significant
ATP recovery occurred after 24 hr in the control dogs, but in the
ribose-treated animals,
ATP levels rebounded to 85% of control by 24 hr.(ABSTRACT TRUNCATED AT 250 WORDS)