Separation of large mammalian ventricular myosin differing in ATPase activity.
To investigate a possible heterogeneity of human ventricular myosin, papillary muscles of patients with valvular dysfunction were examined using a modified native gel electrophoresis. Myosin was separated into 2 components termed VA and VB, whereby the VA to VB proportion appeared to depend on the ventricular load. The proportion of the faster migrating band VA was correlated (P<0.05) with end-diastolic pressure and the aortic pressure-cardiac index product. The regression based on these variables accounted for 67% of the variation in VA (R2=0.67). The VA proportion was, however, not significantly correlated with cardiac norepinephrine concentration. The ATPase activity of the 2 components of myosin was assessed from the Ca3(PO4)2 precipitation by incubating the gel in the presence of ATP and CaCl2. The ATPase activity of VA was 60% of that of VB. The VA and VB forms were observed also in the cat (31.4% VA), dog (32.1% VA), pig (28.5% VA), wild pig (33.7% VA), and roe deer (30.5% VA). VA and VB were not detected in the rat exhibiting the 3 isoforms V1, V2, and V3, rabbit (100% V3), and hare (86% V1). The data demonstrate a heterogeneity of large mammalian ventricular myosin, whereby an increased cardiac load appeared to be associated with a higher myosin VA proportion that exhibited a reduced ATPase activity.
Rupp
Heinz
H
Molecular Cardiology Laboratory, Department of Internal Medicine and Cardiology, Philipps University of Marburg, Karl-von-Frisch-Strasse 1, 35033 Marburg, Germany. rupp@staff.uni-marburg.de
Maisch
Bernhard
B
D000818:Animals; D001794:Blood Pressure; D002122:Calcium Chloride / Q000494:pharmacology; D002302:Cardiac Output; D002415:Cats; D003670:Deer; D004285:Dogs; D004591:Electrophoresis, Polyacrylamide Gel; D034621:Hares; D006352:Heart Ventricles / Q000201:enzymology*; D006801:Humans; D008875:Middle Aged; D008944:Mitral Valve Insufficiency / Q000378:metabolism / Q000503:physiopathology; D008946:Mitral Valve Stenosis / Q000378:metabolism / Q000503:physiopathology; D009218:Myosins / Q000737:chemistry / Q000378:metabolism*; D010210:Papillary Muscles / Q000201:enzymology*; D011817:Rabbits; D051381:Rats; D011918:Rats, Inbred SHR; D017208:Rats, Wistar; D034421:Sus scrofa; D016276:Ventricular Function
D009218:Myosins; D002122:Calcium Chloride