N omega-nitro-L-arginine, an inhibitor of nitric oxide synthesis, decreases noradrenaline outflow in rat isolated perfused mesenteric vasculature.

In the isolated perfused rat mesenteric vasculature with intestine attached N omega-nitro-L-arginine (L-NNA) (30 mumol/l), an inhibitor of nitric oxide (NO) synthesis from L-arginine, did not alter spontaneous noradrenaline outflow. Transmural field stimulation (2-10 Hz) caused a frequency-dependent increase in noradrenaline outflow. The evoked overflow was reduced by L-NNA. L-Arginine (0.3 mmol/l) attenuated the inhibition of noradrenaline overflow by L-NNA. These results suggest that NO increases the release of noradrenaline in rat mesenteric vasculature.