This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Candau, R. Articles by Lionne, C. Search for Related Content PubMed PubMed Citation Articles by Candau, R. Articles by Lionne, C.

At Physiological Temperatures the ATPase Rates of Shortening Soleus and Psoas Myofibrils Are Similar

R. Candau ^*, B. Iorga ^*, F. Travers , T. Barman ^* and C. Lionne 

^* Institut National de la Santé Et de la Recherche Médicale Unité 128, 34293 Montpellier Cedex 5, France; and Unité Mixte de Recherche 5121, Centre National de la Recherche Scientifique/Université Montpellier I, Institut de Biologie, 34960 Montpellier Cedex 2, France

Correspondence: Address reprint requests to Dr. Corinne Lionne, UMR 5121, CNRS/Université Montpellier I, Institut de Biologie, 4 bd Henri IV (CS 89508), 34960 Montpellier Cedex 2, France. Tel.: 33-467-600-231; Fax: 33-467-600-235; E-mail: corinne.lionne{at}univ-montp1.fr.

We obtained the temperature dependences of the adenosine triphosphatase (ATPase) activities (calcium-activated and relaxed) of myofibrils from a slow muscle, which we compared with those from a fast muscle. We chose rabbit soleus and psoas because their myosin heavy chains are almost pure: isoforms I and IIX, respectively. The Arrhenius plots of the ATPases are linear (4–35°C) with energies of activation for soleus myofibrils 155 kJ mol^-1 (activated) and 78 kJ mol^-1 (relaxed). With psoas myofibrils, the energies of activation were 71 kJ mol^-1 (activated) and 60 kJ mol^-1 (relaxed). When extrapolated to 42°C the ATPase rates of the two types of myofibril were identical: 50 s^-1 (activated) and 0.23 s^-1 (relaxed). Whereas with psoas myofibrils the K_m for adenosine triphosphate (activated ATPase) is relatively insensitive to temperature, that for soleus myofibrils increased from 0.3 µM at 4°C to 66.5 µM at 35°C. Our results illustrate the importance of temperature when comparing the mechanochemical coupling in different types of muscle. We discuss the problem of how to reconcile the similarity of the myofibrillar ATPase rates at physiological temperatures with their different mechanical properties.

This article has been cited by other articles:

				R. Rossi, M. Maffei, R. Bottinelli, and M. Canepari Temperature dependence of speed of actin filaments propelled by slow and fast skeletal myosin isoforms J Appl Physiol, December 1, 2005; 99(6): 2239 - 2245. [Abstract] [Full Text] [PDF]