Abstract
The cellular ATP concentration of Spirulina platensis increased when cAMP was added at a low concentration of 0.02 mM. The increase in ATP accompanied a decrease of ADP and AMP. The presence of a high concentration of Na+ (0.22 M) remarkably intensified the effect of cAMP. A Na+ channel blocker, amiloride, and a Na+ ionophore, monensin, suppressed the cAMP-dependent increase in cellular ATP. A H+ ionophore, carbonyl cyanide m-clorophenylhydrazone, which inhibits the activity of FoF1 ATP synthase, did not affect the cAMP-dependent rise in ATP. It is suggested that cAMP stimulates the formation of ATP coupled directly with the translocation of Na+.
