Figure 3. Intravenous administration of L-NNA (20 mg/kg intravenous) decreases the baseline rCBF and increases the regional cerebrovascular resistance (rCVR) measured at 45 min after L-NNA in wild-type mice; 129/SV and C57BL/6, and nNOS knockout mice (nNOS sup -/-). The effects of L-NNA on rCBF or rCVR are not different among the three strains of mice. D-NNA has no significant effect on baseline rCBF and rCVR in any of the three strains. Data are expressed as mean +/- SEM, n = 5–7 animals. *P < 0.01 L-NNA vs. D-NNA.