Long-term isoprenaline administration and its effect on the revascularisation and regeneration of skeletal muscle transplants in mice.

The long-term administration of the beta 2-agonist isoprenaline (at 2 dosages: 100 micrograms/kg or 300 micrograms/kg) was investigated for its effect on the revascularisation and regeneration of skeletal muscle transplants in mice, and also to determine if there was a dose dependent effect. Morphometric, histological and autoradiographic techniques were employed for the investigation. It was found that the accelerated revascularisation observed in a previous short-term study on the effects of isoprenaline did not occur in longer-term usage (as evidenced by autoradiographic and histological results). However, in the present study, the numbers of presumptive satellite cells (identified by autoradiographic examination) were increased at both dosages in the isoprenaline-treated mice. Significant differences were seen in a number of the parameters examined morphometrically, both between the 2 groups which received isoprenaline, and between these groups and the controls (particularly in the volume of regenerated muscle). Dose dependency was therefore evident between the 2 isoprenaline doses and it was concluded that the increased volume of regenerated muscle seen in these transplants was due to the hypertrophic effect of isoprenaline.