The expression of soluble guanylate cyclase in the vasculature of rat skeletal muscle.

Nitric oxide (NO) has various roles in the skeletal musculature in both normal and pathological conditions. NO primarily activates soluble guanylate cyclase (sGC) and mediates subsequent intracellular signaling in target cells. We sought to identify the target cells of NO in the rat skeletal musculature, using subtypes of sGCalpha1 and sGCbeta1 antibodies. Immunohistochemistry revealed that both antibodies stained the same cells with round or oval shapes, having several long processes. The sGC-immunopositive cells co-expressed NG2 chondroitin sulfate proteoglycan, a marker of pericytes. The sGC-immunopositive cells were associated with capillaries and formed cellular networks with elongated cytoplasmic processes. sGCalpha1 and sGCbeta1 were not found in muscle sarcolemma that were stained by anti-dystrophin, or neuromuscular junctions, as detected by anti-synaptophysin. Based on these findings, we concluded that sGC immunoreactivity was specifically distributed in capillary pericytes. Pericytes in the skeletal musculature have been shown to be target cells of NO and are involved in the microvascular blood flow.