Right ventricular trabeculae demonstrated a 35% greater maximum mechanical efficiency than left ventricular trabeculae (13.6% vs. 10.2%), offset by the greater metabolic cost of activation in the LV.
The higher mechanical efficiency of right ventricular trabeculae compared to left ventricular trabeculae is driven by differences in activation heat rather than crossbridge efficiency.
Absolute Event Rate: 13.6% vs 10.2%
We compare the energetics of right ventricular and left ventricular trabeculae carneae isolated from rat hearts. Using our work-loop calorimeter, we subjected trabeculae to stress-length work (W), designed to mimic the pressure-volume work of the heart. Simultaneous measurement of heat production (Q) allowed calculation of the accompanying change of enthalpy (H = W + Q). From the mechanical measurements (i.e. stress and change of length), we calculated work, shortening velocity and power. In combination with heat measurements, we calculated activation heat (Q(A)), crossbridge heat (Q(xb)) and two measures of cardiac efficiency: 'mechanical efficiency' ((mech) = W/H) and 'crossbridge efficiency' ((xb) = W/(H - Q(A))). With respect to their left ventricular counterparts, right venticular trabeculae have higher peak shortening velocity, and higher peak mechanical efficiency, but with no difference of stress development, twitch duration, work performance, shortening power or crossbridge efficiency. That is, the 35% greater maximum mechanical efficiency of right venticular than left ventricular trabeculae (13.6 vs. 10.2%) is offset by the greater metabolic cost of activation (Q(A)) in the latter. When corrected for this difference, crossbridge efficiency does not differ between the ventricles.
Han et al. (Ter,) conduziram outro estudo na bioenergética das trabeculações carnais do coração de rato. As trabeculações do ventrículo direito vs. ventrículo esquerdo foram avaliadas quanto à máxima eficiência mecânica. As trabeculações do ventrículo direito demonstraram uma eficiência mecânica máxima 35% maior do que as trabeculações do ventrículo esquerdo (13,6% vs. 10,2%), compensada pelo maior custo metabólico de ativação no VE.
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