Collagen Gene Expression in Pressure Overloaded Rat Myocardium

Left ventricular hypertrophy is based on cardiac myocyte growth. The hypertrophic process can be considered heterogeneous based on whether it also includes a remodeling and accumulation of fibrillar types I and III collagens that are responsible for impaired myocardial stiffness. In the heart, the messenger RNA (mRNA) for fibrillar collagen types I and III has been detected only in cardiac fibroblasts, whereas mRNA for basement membrane collagen type IV is present in both fibroblasts and myocytes. We studied the early and long-term expression of these collagenous proteins in rat myocardium after abdominal aortic banding with renal ischemia. Complementary DNA probes for rat pro-af(I), mouse type III and mouse type IV collagens, and chicken f-actin were used. Northern and dot blot analysis on total RNA extracted from left ventricular tissue indicated a sixfold increase in steady-state levels of mRNA for collagen type