Experimental observation shows a linear relationship between oxygen consuptfon and the measured pressure-volume area in the pressure-volume plan. The biochemical-mechanical basis for this linear relationship between left ventricular (LV) energy consuption and the generated mechanical energy Is established here. Biochemical studies and the analysis of calcium kinetics and Xb cycling suggest the existence of two main intracellular feedback mechanisms: 1). A positive feedback mechanism, the cooperattvity, whereby the affinity of the regulatory proteins for caldum depends on the number of force producing Xbs, and 2). A mechanical feedback, whereby the rate of Xb conformation change depends linearly on the filament sliding velocity. The cooperatrvtty mechanism determines the force-length relation, while the mechanical feedback determines the force-velocity relation. The ATP is consumed by the actomyosin ATPase while the Xbs turn to the strong force generating conformation. The cooperatMty regulates Xb ATPases recruitment, hence the rate of ATP hydrolysis and energy consumption. The mechanical feedback determines the generated power and Xb weakening. These feedback loops determine the dépendance of the number of available actomyosin ATPase and thus the effect of loading condition on the rate of energy consumption. Sponsored by the Levy-Eshkot Fellowship of the Ministry of Science and Arts and the Technion VP fund for promoting research.
|Original language||English (US)|
|State||Published - 1996|
ASJC Scopus subject areas
- Agricultural and Biological Sciences (miscellaneous)
- Biochemistry, Genetics and Molecular Biology(all)
- Cell Biology