Capillary Red Blood Cell Velocity Is Decreased in Skeletal Muscle of Septic Rats: In Vivo Imaging Using...

This study aimed to investigate the impact of sepsis on red blood cell (RBC) velocity, diameter, and categories of skeletal muscle capillaries 3-4 h after sepsis onset. Male Wistar rats (9-11 weeks old, n = 14) were randomly classified into sham and cecal ligation and perforation (CLP) groups, respectively. In vivo imaging of capillaries in the spinotrapezius muscle was performed using stain-free videocapillaroscopy. RBC velocity and capillary diameter were analyzed. Capillaries were classified into three groups: (1) continuously flowing capillaries defined as maintaining continuous flow for >30 s; (2) intermittently flowing, showing brief stagnation lasting <10 s; (3) stopped-flow, showing no flow for >10 s during 30 s of observation periods. The number of capillaries in each category is compared between the groups. The RBC velocity of the CLP group was significantly lower than that of the sham group (p = 0.01), but the capillary diameter was not different between the groups. The CLP group showed a trend of a weak negative correlation between capillary diameter and RBC velocity (r² = 0.16, p = 0.08), but the sham group did not. No significant difference was observed between the groups in each capillary category. These results suggest that sepsis decreases RBC velocity in resting skeletal muscle capillaries but has no effect on capillary category or diameter.