Muscle Physiology

Professor Nancy Curtin, Head of Group

Our focus is energy turnover during contraction of skeletal muscle. The energy from ATP breakdown is converted into mechanical work and heat by the contractile process.

ATP -> ADP + Pi + work + heat

We measure work and heat; the sum of the two is proportional to the amount of ATP used, in other words, the cost of contraction. The ratio, work/(work +heat), is a measure of efficiency.

Our particular expertise is measuring heat production by detecting the small increase in muscle temperature (a fraction of a degree) during contraction using arrays of thermocouples we make in the lab.

We use isolated muscles removed from the animal, so the pattern of stimulation and movement can be matched to what happens in vivo, to guarantee relevance to locomotion. Fish muscle (see image) has been particularly useful; the different muscle fibre types (white and red) are well segregated (inset image), easy to isolate separately and extremely robust. We have shown the white fibres are more powerful and shorten faster than red fibres, but whites are less efficient and have much less endurance than reds.

We have also used muscle from frogs, lizards, mice, lamprey, eel, squid and sepia, and are now studying papillary muscles from hearts of wild type and transgenic mice with Professor S Marston and Dr W Song.

Through our collaboration with Professor R Woledge we have a strong commitment to mathematical simulations aimed at discovering how well current models of the crossbridge cycle can account for the force, heat and ATP turnover.

We have on-going collaborations with Professor M Ferenczi (Imperial), Dr C Barclay (Griffith Univ, Australia), Professor P Aerts (Antwerp) and Dr W Van der Laarse (Amsterdam).

Selected Publications

West TG; Curtin NA; Ferenczi MA; He ZH; Sun YB; Irving M; Woledge RC. (15 Feb 2004). Actomyosin energy turnover declines while force remains constant during isometric muscle contraction. J Physiol. 555:27-43.

Barclay CJ; Woledge RC; Curtin NA. (Jan 2010). Inferring crossbridge properties from skeletal muscle energetics. Prog Biophys Mol Biol. 102:53-71.

Curtin, N.A., Lou, F. & Woledge, R.C. (accepted). Sustained performance by red and white muscle fibres from the dogfish, Scyliorhinus canicula. J. exp. Biol.