Fig. 1.

Averaged microvascular O₂ driving pressure (Po₂mv) from results (n = 3) during 180 s of NaNO₂ superfusion (30 mM in Krebs-Henseleit solution) and a bolus (~10 s) intra-arterial infusion of NaNO₂ (7 mg/kg in 0.4 ml heparinized saline solution). Inset: black box denotes the superfusion period. Measurements were recorded for an additional 600 s to monitor the effects of direct vs. systemic administration in the absence of muscle contraction. Following the bolus intra-arterial infusion Po₂mv declined at a rate of −0.098 mmHg/s (regression not shown) before returning to baseline levels. In the superfusion condition, following the initial increase and plateau in Po₂mv, there was a decline in Po₂mv at the rate of −0.012 mmHg/s. Data are presented as means ± SE every 30 s throughout each condition.