Nitric oxide bioavailability modulates the dynamics of microvascular oxygen exchange during recovery from contractions

Aim: Lowered microvascular PO2 (PO2mv) during the exercise off‐transient likely impairs muscle metabolic recovery and limits the capacity to perform repetitive tasks. The current investigation explored the impact of altered nitric oxide (NO) bioavailability on PO2mv during recovery from contractions in healthy skeletal muscle. We hypothesized that increased NO bioavailability (sodium nitroprusside: SNP) would enhance PO2mv and speed its recovery kinetics while decreased NO bioavailability (l‐nitro arginine methyl ester: l‐NAME) would reduce PO2mv and slow its recovery kinetics. Methods: PO2mv was measured by phosphorescence quenching during transitions (rest–1 Hz twitch‐contractions for 3 min–recovery) in the spinotrapezius muscle of Sprague–Dawley rats under SNP (300 μm), Krebs‐Henseleit (Control) and l‐NAME (1.5 mm) superfusion conditions. Results: Relative to recovery in Control, SNP resulted in greater overall microvascular oxygenation as assessed by the area under the PO2mv curve (PO2 AREA; Control: 3471 ± 292 mmHg s; SNP: 4307 ± 282 mmHg s; P