title: Myocardial changes during the progression of left ventricular pressure-overload by renal hypertension or aortic constriction: myosin, myosin ATPase and collagen.
abstract: We measured the interrelationships between ventricular muscle myosin mass, myosin ATPase activity and collagen in cats with varying degrees of hypertrophy from left ventricular (LV) pressure-overload produced by either aortic banding or renal hypertension. In order to compare two models of LV pressure-overload with different time courses of progression, the results were analyzed as a function of LV mass or LV weight/body weight (LV/BW) ratio. Myosin was quantitated by SDS-polyacrylamide gel electrophoresis and hydroxyproline was measured as an index of collagen. Myosin concentration was positively correlated with increasing LV mass in control cats. However, in pressure-overloaded LV, myosin concentration was elevated and nearly constant for LV less than 9.0 g, but decreased in LV greater than 9.0 g. Myosin concentration in pressure-overloaded LV was greatest before a significant increase in LV/BW ratio. Hydroxyproline concentration was inversely related to myosin concentration in both LV pressure-overload models and increased with the severity of hypertrophy. Actomyosin ATPase activity in pressure-overloaded LV, was not significantly different from control over a wide range of LV/BW ratios. However, absolute myosin ATP hydrolysis in pressure-overloaded LV, increased by as much as 40%, relative to control, due primarily to increased myosin. The changing spectrum and interrelationships of myosin and collagen were independent of the mechanism of pressure-overload, but were correlated with the severity of hypertrophy.
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism*; D000818:Animals; D001018:Aortic Diseases / Q000150:complications / Q000503:physiopathology; D001157:Arterial Occlusive Diseases / Q000150:complications / Q000503:physiopathology; D001794:Blood Pressure; D001835:Body Weight; D006332:Cardiomegaly / Q000209:etiology / Q000378:metabolism* / Q000503:physiopathology; D002415:Cats; D003094:Collagen / Q000378:metabolism*; D006909:Hydroxyproline / Q000032:analysis; D006977:Hypertension, Renal / Q000150:complications / Q000503:physiopathology; D009206:Myocardium / Q000201:enzymology / Q000378:metabolism*; D009218:Myosins / Q000032:analysis / Q000378:metabolism*; D009929:Organ Size
chemical_list: D003094:Collagen; D000251:Adenosine Triphosphatases; D009218:Myosins; D006909:Hydroxyproline