Type IV collagen and its degradation in paralyzed human muscle: effect of functional electrical stimulation.

The purpose of this study was to evaluate the effects of spinal cord injury (SCI) and functional electrical stimulation (FES) of paralyzed muscles on type IV collagen content and proteins involving its degradation, which is initiated by matrix metalloproteinase (MMP)-2 and -9 and regulated by their tissue inhibitors (TIMPs)-2 and -1. Ten SCI subjects participated in an 18-month program of functional electrical stimulation (FES) of their leg muscles. Needle biopsies were taken from the vastus lateralis muscle before and at various times during the training period, and from able-bodied controls. Type IV collagen concentration was unaltered. ProMMP-2 level of SCI subjects before the training period tended to be higher than able-bodied controls and was significantly above the control level after FES. MMP-9 concentration was unchanged. The results suggest accelerated type IV collagen turnover in skeletal muscle of SCI individuals especially after FES as a part of adaptive process of the muscle. Copyright 2000 John Wiley & Sons, Inc.