Figure 2: Effects of an nNOS inhibitor, SMTC, in the cerebrospinal fluid of Dahl salt-sensitive rats on the maximum RSNA induced by hypotension. DS0.4%: Dahl salt-sensitive rats fed a regular diet; DS8%: Dahl salt-sensitive rats fed a high-salt diet; Oc with bar line: gradual caval occlusion in which the inferior vena cava was occluded in a ramp manner with a perivascular occluder. AP: arterial pressure; MAP: mean arterial pressure; HR: heart rate; RSNA: renal sympathetic nerve activity; mean RSNA: mean RSNA expressed as a %; aCSF icv: intracerebroventricular infusion of artificial cerebrospinal fluid (control groups); SMTC icv: intracerebroventricular infusion of 50 nmol S-methyl-L-thiocitrulline, an nNOS inhibitor [37]. Each arrow indicates a peak response of mean RSNA to a ramp decrease in MAP by caval occlusion. RSNA signals after these peak responses were produced by animal movements because of hypotension. Both resting RSNA and the peak response obtained by the release of baroreflex-mediated negative feedback inhibition (baroreceptor-unloaded RSNA, which indicates central sympathetic activity generated before baroreflex inhibition) were markedly increased after SMTC infusion [39].