RESUMO
The regulation of adenylyl cyclase activity by nitric oxide (NO) was studied in rat (Sprague-Dawley) striatal membranes. Three chemically distinct NO donors attenuated forskolin-stimulated activity but did not alter basal activity. Maximum inhibition resulted in a 50% decrease in forskolin-stimulated activity, consistent with the presence of multiple isoforms of adenylyl cyclase and our previous findings that only the forskolin-stimulated activity of the type-5 and -6 isoform family of enzymes is inhibited by NO. To monitor primarily the type-5 isoform, we examined the ability of NO donors to attenuate D(1)-agonist-stimulated adenylyl cyclase activity. Under those conditions, complete inhibition was observed. The data indicate that NO attenuates neuromodulator-stimulated cAMP signaling in the striatum.
