Figure 1. Experiment timeline.

A, 30 min after catheterization, baseline measurements were taken for 2 min with saline infusion. Subjects performed rhythmic forearm handgrip exercise for 20 min, with either saline or drug continuously infused (2 ml min⁻¹). At 5 min of exercise, l-NAME was infused for 5 min, followed by 2 min saline, then 5 min ketorolac, then 3 min saline, and finally 5 min recovery with saline. The drug order was reversed in 7 of 14 subjects. Arrows indicate approximate times that 30 s average data were collected for analysis, or the approximate time that nadir FBF were taken within l-NAME or ketorolac infusion; the timing of nadir varied between subjects (see Results). B, in 8 of the 14 subjects, l-NAME (2.5 mg ml⁻¹) and ketorolac (300 μg ml⁻¹) were infused at 1 ml min⁻¹ each for 20 min after the first 20 min exercise bout. After this 30 min rest period, subjects performed 5 min forearm exercise at the same workload with concurrent infusion of l-NAME and ketorolac (both 1 ml min⁻¹). FBF was measured for 2 min at rest, during exercise, and at 5 min recovery.