Nitric oxide-independent cGMP efflux in the striatum of rats exposed to carbon monoxide as determined by microdialysis.

Extracellular cGMP in the striatum of rats exposed to 3000 ppm carbon monoxide (CO) or 8% O2 was decreased during the early period of exposure. Thereafter, extracellular cGMP in rats exposed to CO, but not 8% O2, was transiently increased. A nitric oxide (NO) synthase inhibitor, NG-nitro-L-arginine, strongly reduced the steady-state level of extracellular cGMP in the striatum, indicating a primary role of NO in cGMP production. However, it failed to suppress the CO-induced increase in extracellular cGMP in the striatum. These findings suggest that CO may stimulate cGMP production in rat striatum independently of NO and hypoxia.