Regulation of capillary hemodynamics by KATP channels in resting skeletal muscle

Superfusion of the rat spinotrapezius muscle with the sulfonylurea glibenclamide (GLI) was used to locally inhibit KATP channelsin vivo. GLI reduced both red blood cell (RBC) flux and velocity thereby impairing perfusive microvascular O2 transport and lengthening RBC capillary transit times, respectively. These results support that KATP channels regulate capillary hemodynamics and microvascular gas exchange in resting skeletal muscle. AbstractATP ‐sensitive K+ channels (KATP) have been implicated in the regulation of resting vascular smooth muscle membrane potential and tone. However, whether KATP channels modulate skeletal muscle microvascular hemodynamics at the capillary level (the primary site for blood ‐myocyte O2 exchange) remains unknown. We tested the hypothesis that KATP channel inhibition would reduce the proportion of capillaries supporting continuous red blood cell (RBC) flow and impair RBC hemodynamics and distribution in perfused capillaries within resting skeletal muscle. RBC flux (fRBC), velocity (VRBC), and capillary tube hematocrit (Hctcap) were assessed via intravital microscopy of the rat spinotrapezius muscle (n = 6) under control (CON) and glibenclamide (GLI; KATP channel antagonist; 10  µM) superfusion conditions. There were no differences in mean arterial pressure (CON:120 ± 5, GLI:124 ± 5 mmHg;p >  0.05) or heart rate (CON:322 ± 32, GLI:337 ± 33 beats/min;p >  0.05) between conditions. The %RBC‐flowing capillaries were...

Source: Physiological Reports - May 1, 2021 Category: Physiology Authors: Daniel M. Hirai, Ayaka Tabuchi, Jesse C. Craig, Trenton D. Colburn, Timothy I. Musch, David C. Poole Tags: ORIGINAL ARTICLE Source Type: research