Fibrillolysis and electrophoretic determination of actin and myosin in hypertrophied human myocardium.

Destructive myofibrillar lesions, particularly degenerative fibrillolysis in hypertrophied hearts, were studied with the electron microscope in left ventricular myocardium samples obtained from autopsies with post mortem periods not exceeding 195 min. The contractile protein composition of these samples was determined electrophoretically. 18 cases were studied, grouped as follows: Group I, composed of 5 cases showing normal hearts which were employed in the determination of normal electrophoretic values. Group II: 10 cases with hypertrophic hearts, 1 of them showing contraction bands and decreased myosin, 6 others with fibrillolytic lesions of which 3 presented a decrease in myosin and 3 possessed normal myosin values. None of the cases showed a decrease in actin values. Group III was composed of 3 cases of hearts with normal weights that showed ultrastructural alterations of the myofibrils: 1 with myofibrillar disarray and normal electrophoretic values, 1 with incomplete contraction bands and normal protein values and 1 with focal myofibrillar disgregation and myosin decrease. It is concluded that in some cases of degenerative fibrillolytic lessions a decrease of myosin occurs. The method employed does not rule out that apparently normal actin and myosin values might be due to the presence of contractile proteins in a denatured state that does not affect their electrophoretic mobility.