Plasma concentrations of l-NMMA following a single i.v. dose of 3 mg kg−1 over 5 min and pharmacodynamic effects on cardiac output (CO, □), fundus pulsation amplitude (FPA, •), and exhaled NO (exhNO, ◊), which are presented as percentage reduction from the baseline values. Data are from study 1 and are presented as means±s.d., n=7.