Cardiac myosin phenotype remodeling following chronic spinal transection

Spinal transection results in profound neural and functional changes of the heart. However, phenotypic alterations in cardiac myosin heavy chains (MyH C) as a result of spinal transection have not been explored. Hearts were re moved from 180 day old rats who had their spinal cords transected between T 6 and T9 (ST; n = 10) and intact controls (IN; n = 9). Myosin was isolated from the left and right ventricles and separated into its respective heavy chain components (designated as alpha and beta) by SDS-PAGE. The resulting gels were scanned with a laser scanning densitometer to obtain relative con centrations of these two heavy chains. The left ventricles of the ST rats h ad a significantly higher (p < 0.05) alpha to beta ratio (10.89) than the i ntact controls (4.20), while the right ventricle of the ST rats had a signi ficantly lower (p < 0.05) alpha to beta ratio (7.49) relative to intact con trols (13.62). The left and right ventricular weight to body weight ratios were not different in ST compared to IN. Additionally, there were significa nt within group differences (p < 0.05) between the alpha and beta MyHC rati os for the left and right ventricles. These data suggest that 1) spinal tra nsection causes remodeling of the right and left ventricles and 2) the two ventricles do not remodel as a unit.