The induction of c-fos and c-jun in the stretched latissimus dorsi muscle of the rabbit: responses to duration, degree and re-application of the stretch stimulus.

The mRNA levels of the proto-oncogenes c-fos and c-jun were measured in the rabbit latissimus dorsi (LD) muscle in response to the application of various stretch regimes in vivo. It was shown that it was necessary for the stretch to be applied continuously over 1 h in order to achieve full induction of c-fos and c-jun mRNA at 1 h. In addition, a correlation was demonstrated between the degree of stretch imposed on the LD and the induced levels of c-fos and c-jun mRNA. Moreover, a second induction of these genes occurred when the LD was subjected to a second stretch stimulus. The magnitude and time course of the second response depended on the precise timing of the second stimulus in relation to the initial induction.