Year: 2024
Type: article
Abstract: Cardiac sex-difference functional studies have centred on measurements of twitch force and Ca 2+ dynamics. The energy expenditures from these two cellular processes: activation (Ca 2+ handling) and contraction (cross-bridge cycling), have not been assessed, and compared, between sexes. Whole-heart studies measuring oxygen consumption do not directly measure the energy expenditure of these activation-contraction processes. In this study, we directly quantified these energy expenditures in terms of heat production. Left-ventricular trabeculae were dissected from rats aged 9–13 weeks. Mechano-energetics of trabeculae were characterized using our work-loop calorimeter under various conditions including varying muscle lengths, stimulus frequencies, and afterloads. Each trabecula was subjected to protocols that allowed it to contract either isometrically or shorten to perform work-loops. Force production, length change, and heat output were simultaneously measured. We extracted various metrics: twitch kinetics, shortening kinetics, mechanical work, and heat associated with cross-bridge cycling and Ca 2+ cycling, and quantified mechanical efficiency. Results show no sex differences in any of the metrics. Peak mechanical efficiency was not affected by sex (10.25 ± 0.57% in female trabeculae; 10.93 ± 0.87% in male trabeculae). We conclude that cardiac mechanics and energetics are not affected by sex at the muscle level, within the rat age range studied.
Source: Scientific Reports
Authors: Maryam Rahmani, Toan Pham, David J. Crossman, Kenneth Tran, Andrew J. Taberner, June-Chiew Han
Institution: University of Auckland
Language: English
Subfield: Cardiology and Cardiovascular Medicine
Field: Medicine
Domain: Health Sciences
Open Access status: gold
Estimated APC paid: $2,590
OpenAlex ID: W4405854815