Introduction 

In MLC/mIGF1 transgenic model, IGF1 gene is regulated by the promoter of myosin light chain (MLC) which only in fast fibres produces autocrine IGF1. From the 5th week after birth, these animals show muscle hypertrophy and consequent increased muscle strength in respect to wild type. It is well known that the muscle reparative/regenerative machinery derives from the recruitment of satellite cell pool, strongly influenced by gene activation and environment conditions. The aim of this work is to verify if the overexpression of IGF1 is able to modify some functional features of satellite cells during the differrentiative process. In particular, we focused our attention on the analyses of parameters directly involved in excitation-contraction cycle (Ca²⁺ handling and sarcolemmal electrical properties).

Methods 

Videoimaging on single cells was used to monitor intracellular calcium variations, and patch clamp technique in whole cell configuration to assay membrane electric properties.

Results 

The results showed an increased functional DHPR-binding and increased outward potassium currents in satellite cells derived from MLC/mIGF1 mice in respect to those from wild type animals. Transgenic satellite cells appeared differently sensitive to ATP and ACh stimuli, both physiological regulatory factors of muscle activity.

In conclusion, these preliminary data showed that a higher mIGF1 level could directly influence the fibre capacity to activate the contractile apparatus.