Figure 5.

Under resting conditions, infusion of N^g‐monomethyl‐l‐arginine (l‐NMMA) in 5 normotensive male volunteers increased mean arterial pressure (MAP) significantly by about 10% but had no effect on muscle sympathetic nerve activity (MSNA), measured by microelectrodes inserted selectively into muscle nerve fasciculi of the peroneal nerve posterior to the fibular head. By contrast, infusion of phenylephrine (PE), a nitric oxide‐independent vasoconstrictor, increased MAP to a similar extent but also decreased MSNA by about 50%. Coinfusion of nitroprusside (NP) with l‐NMMA resulted in reversal of the increase in MAP observed with l‐NMMA alone, but also resulted in a significant increase in MSNA. *P<.05 vs baseline. Reproduced with permission from Owlya et al. ⁹⁸