Figure 4. Effects of systemic nitric oxide synthase inhibition with l-NMMA on blood pressure in healthy male subjects with high vs. low levels of baseline muscle sympathetic nerve activity.

Low- and moderate-dose nitric oxide synthase inhibition causes larger increases in blood pressure in the subset of subjects with high baseline levels of MSNA. *P < 0.05, differences between the groups. Data from Charkoudian et al. (2006). Open circles = high MSNA subjects; closed circles = low MSNA subjects.