Myocardial functional correlates of cardiac myosin light chain 2 phosphorylation

• Published in: Journal of applied physiology (1985) Vol. 68; no. 6; p. 2426
• Main Authors: Fitzsimons, D P, Bodell, P W, Baldwin, K M
• Format: Journal Article
• Language: English
• Published: United States 01.06.1990
• Subjects: Animals; Blood Pressure - physiology; Female; Heart - physiology; Heart Rate - physiology; Hemodynamics - physiology; Myocardial Contraction - physiology; Myocardium - metabolism; Myosins - metabolism; Phosphorylation; Physical Exertion - physiology; Rats; Rats, Inbred Strains
• ISSN: 8750-7587; 1522-1601
• DOI: 10.1152/jappl.1990.68.6.2426

In vitro and in situ studies have proposed a potentiation of submaximal force production after myosin light chain 2 (P-light chain) phosphorylation in mammalian striated muscle. The purpose of this study was to ascertain the relationship between the augmentation in left ventricular pressure development and cardiac myosin P-light chain phosphorylation at different times during and after submaximal treadmill exercise involving adult female Sprague-Dawley rats. In vivo hemodynamic measurements were monitored with an indwelling high-fidelity solid-state pressure transducer. Exercise heart rate, peak left ventricular (LV) pressure, and rate of LV pressure development/relaxation (LV +/- dP/dt) were significantly elevated compared with a normal sedentary group (P less than 0.001). Peak LV pressure remained significantly elevated throughout 20 min of postexercise recovery (P less than 0.01), and heart rate, LV end-diastolic pressure, and LV +/- dP/dt returned rapidly to preexercise values. Corresponding to these in vivo hemodynamic changes, increased levels of P-light chain phosphorylation were observed during both exercise (16%, P less than 0.01) and subsequent recovery periods (14%, P less than 0.02) compared with the NC group. A quasi-temporal relationship was observed between postexercise peak LV pressure potentiation and P-light chain phosphorylation. These results demonstrate that cardiac myosin P-light chain phosphorylation is associated, in part, with the augmentation of peak LV pressure observed during both exercise and recovery.