Does the intercept of the heat-stress relation provide an accurate estimate of cardiac activation heat?
Toan Pham, Kenneth Tran, Kimberley M Mellor, Anthony Hickey, Amelia Power, Marie-Louise Ward, Andrew Taberner, June-Chiew Han, Denis Loiselle
The Journal of Physiology | Published : 2017
KEY POINTS: The heat of activation of cardiac muscle reflects the metabolic cost of restoring ionic homeostasis following a contraction. The accuracy of its measurement depends critically on the abolition of crossbridge cycling. We abolished crossbridge activity in isolated rat ventricular trabeculae by use of blebbistatin, an agent that selectively inhibits myosin II ATPase. We found cardiac activation heat to be muscle length independent and to account for 15-20% of total heat production at body temperature. We conclude that it can be accurately estimated at minimal muscle length. ABSTRACT: Activation heat arises from two sources during the contraction of striated muscle. It reflects the m..View full abstract