Abstract
It has been considered that satellite cells are responsible for the postnatal growth and regeneration of skeletal muscle. However, the details of mechanism for skeletal muscle regeneration are still unclear. The purpose of this study was to investigate the effects of heat stress on the regeneration processes of injured skeletal muscles. Male Wistar rats (7 weeks old) were divided into control (n = 25), non-heated (n = 50), and heat-stressed groups (n = 50). To induce a necrosis-regeneration cycle, 0.1 mL of cardiotoxin (CTX, 10 μmol/L) was injected into the left tibialis anterior muscle of rats except in the control group. Rats in the heat-stressed group were exposed to environmental heat stress (41°C for 60 min) in a heat chamber 24 hours before or immediately after CTX injection without anesthesia. The tibialis anterior muscles were dissected 1, 3, 7, 14, and 28 days after CTX injection. The muscle protein contents in the heat-stressed group were significantly greater than controls 28 days after CTX injection (p<0.05). Increment in Pax7-positive nuclei, which is a specific indicator for muscle satellite cell, in the heated group was larger than in the non-heated group. These results suggest that heat stress could activate satellite cells, promote the proliferation and the differentiation of satellite cells, and facilitate the regeneration. [Jpn J Physiol 55 Suppl:S117 (2005)]
