YC-1 Ameliorated I/R-Induced Microcirculatory Disturbance in Rat Cremaster Muscle: A Mechanistic Study

The authors' previous study speculated that YC-1, a guanylate cyclase (GC) activator, ameliorated ischemia-reperfusion (I/R)-induced microcirculatory disturbance; however, its underlying mechanism remains largely unknown. This study aimed to investigate the role of the GC, protein kinase C (PKC), and MAP kinase in YC-1's ability to ameliorate I/R-induced microcirculatory disturbances in rat cremaster muscle flaps.

Male Sprague Dawley (SD) rats were randomized (n = 5–8 per group) into seven groups: Group 1, sham-operated control; Group 2, I/R (4 hr of pudic epigastric artery ischemia followed by 1 hr of reperfusion); Group 3, YC-1 (0.2 mg/kg) + I/R; Group 4, YC-1 (0.2 mg/kg) + ODQ (GC − inhibitor, 5 mg/kg) + I/R; Group 5, YC-1 (0.1 mg/kg) + I/R; Group 6, YC-1 (0.1 mg/kg) + ODQ (5 mg/kg) + I/R; Group 7, YC-1 (0.2 mg/kg) + Chelerythrine (PKC-inhibitor, 5 mg/kg) + I/R. Intravital microscopy was used to observe leukocyte/endothelial cell interactions and quantify functional capillaries in cremaster muscles.

Microscopically, they observed that I/R markedly increased the number of rolling, adhering, and transmigrating leukocytes. I/R also markedly decreased the number of functional capillaries. In contrast, pretreatment of YC-1 can ameliorate I/R-induced leukocyte-endothelium adhesive interaction. Compared to the YC-1 treated group, both GC inhibitor (ODQ) and PKC inhibitor (Chelerythrine) antagonized the microcirculatory beneficial effects of YC-1. In addition, YC-1 downregulated I/R-induced E-selectin, L-selectin, TNF-alpha, and IL-1 beta protein expression in rat cremaster muscle were also blocked by ODQ and Chelerythrine.

These results suggest that YC-1 ameliorated I/R-induced microcirculatory disturbance and inhibited pro-inflammatory cytokines protein may occur through both GC and PKC-dependent mechanisms.