Relationship between NO release and FBF. Responses in individual subjects during increasing doses of ACh (1, 3, and 10 μg/min) with and without simultaneous inhibition of eNOS (4, 8, and 12 μmol/min l-NMMA i.a.). Experimental data from 8 individuals are depicted. Spearman rank correlation coefficient for single data points: r = 0.85, r2 = 0.73; P < 0.001.