Exercise Hyperemia Following Ischemia-Reperfusion

Brady Hanson; Kayla Miller; Darren Casey; Satoshi Hanada; Andrew Feider; Aric Aldrich

doi:10.1152/physiol.2023.38.s1.5731658

Prolonged ischemia can result in cellular dysfunction. Paradoxically, the reintroduction of blood flow (reperfusion) can lead to further damage, described as ischemia-reperfusion injury (I/R). It has been reported that I/R attenuates endothelial function at the micro- and macrovascular level. An attenuation in microvascular endothelial function from I/R may therefore disrupt the ability to modulate exercise hyperemia in contracting skeletal muscle. We tested the hypothesis that I/R blunts the rapid and steady-state hyperemic and vasodilatory response to rhythmic handgrip exercise. Ten young healthy subjects (8M/2F; 24 ± 1 yr) completed two separate study visits (I/R and time control trials) in a random order. On each study visit rapid-onset hyperemia and vasodilation following a single forearm contraction was assessed in duplicate. Rhythmic handgrip exercise (20 contractions per min) was then completed for 3 min. All handgrip exercises were performed at 20% maximum voluntary contraction. Following exercise, either I/R was induced (pneumatic cuff placed around the upper left arm at 240 mmHg for 20 min followed by 20 min of reperfusion) or a time control trial (supine rest for 40 min) was completed. Handgrip exercises were then repeated immediately after each respective intervention. Brachial artery blood velocity and diameter were measured with Doppler ultrasound and forearm vascular conductance (FVC) was calculated as forearm blood flow (FBF; ml·min-1) over blood pressure (mmHg). In response to a single muscle contraction, peak hyperemia (ΔFBF from baseline) and vasodilation (ΔFVC) were attenuated following I/R (134 ± 15 vs. 103 ± 13 ml·min-1; 160 ± 17 vs. 118 ± 15 ml·min-1·100 mmHg-1, P<0.05 for both) but not following time control (115 ± 20 vs. 124 ± 18 ml·min-1; 150 ± 25 vs. 148 ± 20 ml·min-1·100 mmHg-1, P=0.16 and P=0.95, respectively). Total FBF and FVC following a single muscle contraction was not different between I/R (25 ± 4 vs. 20 ± 3 ml; 33 ± 5 vs. 24 ± 4 ml·100 mmHg-1) and time control (21 ± 4 vs. 23 ± 4 ml; 28 ± 5 vs. 28 ±4 ml·100 mmHg-1) trials (group x time interactions P=0.05 and P=0.08, respectively). Steady-state ΔFBF and ΔFVC during rhythmic exercise was unchanged in both I/R (192 ± 16 vs. 190 ± 17 ml·min-1; 208 ± 18 vs. 193 ± 19 ml·min-1·100 mmHg-1) and time control (188 ± 17 vs. 196 ± 15 ml·min-1; 206 ± 19 vs. 207 ± 15 ml·min-1·100 mmHg-1) trials (group x time interactions P=0.34 and 0.21, respectively). Our data indicate that 40 min of I/R blunts hyperemia and vasodilation at the onset of skeletal muscle contraction, but does not appear to attenuate these responses during steady-state rhythmic exercise. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Exercise Hyperemia Following Ischemia-Reperfusion

View Online

Abstract

Details

Metrics