LONG-TERM ISOPRENALINE ADMINISTRATION AND ITS EFFECT ON THE REVASCULARIZATION AND REGENERATION OF SKELETAL-MUSCLE TRANSPLANTS IN MICE

The long-term administration of the beta(2)-agonist isoprenaline (at 2 dosages: 100 mu g/kg or 300 mu g/kg) was investigated for its effect on the revascularisation and regeneration of skeletal muscle transplan ts in mice, and also to determine if there was a dose dependent effect . Morphometric, histological and autoradiographic techniques were empl oyed for the investigation. It was found that the accelerated revascul arisation observed in a previous short-term study on the effects of is oprenaline did not occur in longer-term usage (as evidenced by autorad iographic and histological results). However, in the present study, th e numbers of presumptive satellite cells (identified by autoradiograph ic examination) were increased at both dosages in the isoprenaline-tre ated mice. Significant differences were seen in a number of the parame ters examined morphometrically, both between the 2 groups which receiv ed isoprenaline, and between these groups and the controls (particular ly in the volume of regenerated muscle). Dose dependency was therefore evident between the 2 isoprenaline doses and it was concluded that th e increased volume of regenerated muscle seen in these transplants was due to the hypertrophic effect of isoprenaline.