8-bromo-cGMP improves energy state in hypoxic rat atria.

8-bromo-cGMP (1 X 10(-4) M) was found to prevent the hypoxia-induced decrease in creatine phosphate (CrP) and ATP in isolated rat atria. An increase in ADP was also seen after 8-bromo-cGMP treatment, while the AMP level remained unchanged. 8-bromo-cGMP administration resulted in a higher energy charge during the initial state of hypoxia. 8-bromo-cGMP did not affect heart rate or contractility during hypoxia. These results suggest that cGMP improves the energy state of the heart cell in hypoxia. The exact mechanism(s) of these effects is not known but an improvement of oxidative phosphorylation might, quantitatively, account for the changes.