Suppression of Ca(2+)-dependent heat production in mouse skeletal muscle by high fish oil consumption.

The energy dissipation associated with calcium homeostasis amounts to more than 20% of muscle energy expenditure (EE) at rest and can be quantified from microcalorimetric measurements of heat production in response to chemical modulators of sarcoplasmic reticulum (SR) Ca2+ release. Using this approach, Ca(2+)-dependent heat production in both red- and white-fiber muscles from mice fed a high-fat (HF) diet rich in fish oil was found to be significantly lower than in other groups fed HF diets rich in saturated fat (hydrogenated coconut oil) or n-6 polyunsaturated fats corn oil) and in a group fed a low-fat diet. These findings reveal a potentially specific effect of fish oil on muscle-cell energy metabolism via interference with sarcoplasmic calcium homeostasis, and raise the possibility that modification of the energy cost for intracellular calcium homoeostasis may be a cellular mechanism by which diet could modulate skeletal muscle thermogenesis and whole-body EE.