Repeated remote ischemic preconditioning improves temporal characteristics of the cutaneous microvascular responses to postocclusive reactive hyperemia.

Abstract

Repeated remote ischemic preconditioning (RIPC) improves endothelial-dependent cutaneous vasodilation. However, the role of repeated RIPC on the postocclusive reactive hyperemia (PORH) response in the cutaneous microvasculature is unknown; here, we assessed whether repeated RIPC would increase PORH responses. Thirty participants (23 ± 3 yr old) performed either repeated RIPC (1 session/day for a week, n = 10 or 12 sessions over 2 wk, n = 12) or 2-wk control (n = 8). Each RIPC session comprised 4 repetitions of 5-min arm blood flow occlusion interspersed by 5-min reperfusion. PORH was elicited by brachial artery occlusion for 5 min. Cutaneous vascular conductance was determined using laser speckle contrast imaging before and after the repeated RIPC. The control group did not receive RIPC but underwent the PORH measurements 2 wk later. Area under the curve and peak of PORH were not different. Max/Time to Peak, the maximum hyperemia achieved (Max) over the rate of reperfusion following arterial occlusion (Tp), improved similarly after both 1 and 2 wk of repeated RIPC (1 wk: 0.09 ± 0.04 vs. 0.12 ± 0.07, 2 wk: 0.12 ± 0.03 vs. 0.14 ± 0.04 CVC/s, Pre vs. Post, P < 0.05). Tp improved only after 2 wk of RIPC (Tp: 16.5 ± 2.1 vs. 14.8 ± 2.4 s, Pre vs. Post, P < 0.05). The control group responses did not change after 2 wk. Repeated RIPC did not increase the magnitude of the hyperemic response but did alter temporal measures of PORH such as Max/Tp and Tp following cuff deflation.NEW & NOTEWORTHY This study investigated the extent to which 1) repeated RIPC improved PORH-induced cutaneous microvascular reactivity and 2) a longer period of RIPC further improved cutaneous microvascular reactivity. Both 1 and 2 wk of RIPC improved cutaneous microvascular reactivity similarly. However, only 2 wk of RIPC altered temporal PORH variables. These results suggest that repeated RIPC increases cutaneous microvascular reactivity following occlusion, but longer duration RIPC may be needed to alter temporal cutaneous microvascular reactivity.