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Energy expenditure for isometric contractions of right and left ventricular trabeculae over a wide range of frequencies at body temperature. | LitMetric

AI Article Synopsis

  • The study investigated how much energy is used during isometric contractions in heart muscle strips from rats, focusing on differences between the right and left ventricles.
  • Researchers measured heat output and stress production while altering contraction frequency to see how performance changed over time.
  • Results showed that while stress and heat were similar between the two heart muscles, the left ventricle had slower contraction rates and a higher heat-to-stress ratio, indicating less efficient contractions, particularly at higher frequencies.

Article Abstract

We studied the energy expenditure of isometric contractions using both right-ventricular (RV) and left-ventricular (LV) trabeculae isolated from the rat heart. The energy expenditure under isometric contraction presents entirely as heat liberation. Preparations were challenged to perform at various rates of energy demand while accounting for their inevitable time-dependent decline of performance. They were electrically stimulated to contract at 37 °C with a frequency order (between 0.1 Hz and 10 Hz) dictated by a fully-balanced Latin-Square experimental design. We measured, simultaneously, their stress production and heat output. As functions of stimulus frequency, active stress and heat were not significantly different between RV and LV trabeculae. However, contraction kinetics, indexed as the maximal rate of rise and fall of twitch, were lower in the LV trabeculae. The ratio of heat to stress was greater in the LV trabeculae, suggesting that the economy of contraction of the LV trabeculae is lower. Their lower economy became more pronounced at high stimulus frequencies. Our results allow us to assess whether slowing of kinetics is a causative mechanism for improvement of economy of contraction.

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Source
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6586799PMC
http://dx.doi.org/10.1038/s41598-019-45273-1DOI Listing

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