Expression of α‐cardiac and α‐skeletal actin mRNAs in relation to innervation in regenerating and non‐regenerating rat skeletal muscles

Abstract

The expression of α‐cardiac and α‐skeletal actin mRNA in regenerating muscle was examined. Changes in mRNA levels were analyzed in autografted extensor digitorum longus (EDL) muscles in rats using α‐isoform specific synthetic oligonucleotides and β‐actin cDNA as probes. After autografting, the expression of α‐cardiac actin mRNA was induced; concomitantly that of α‐skeletal actin mRNA was reduced. The pattern of α‐actin mRNA expression appeared to be similar to that seen in embryonic skeletal muscle. In order to evaluate the effects of innervation on α‐actin mRNA expression in regenerating muscle, nerveless, standard, and nerve‐intact autografted muscles were examined. More complete innervation facilitated the recovery of α‐skeletal actin mRNA to control levels, but had little effect on the amount of α‐cardiac actin mRNA. We found that regenerating muscle shows the embryonic pattern of α‐actin mRNAs in the early stage and concluded that the recovery of α‐skeletal actin mRNA expression to the adult pattern is influenced by innervation, while α‐cardiac actin mRNA expression is nerve independent. © 1992 Wiley‐Liss, Inc. Copyright © 1992 Wiley‐Liss, Inc.