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This Article Full Text Full Text (PDF) All Versions of this Article: 90/3/417    most recent expphysiol.2004.028316v1 Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend 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 Brotto, M. A. P. Articles by Nosek, T. M. Search for Related Content PubMed PubMed Citation Articles by Brotto, M. A. P. Articles by Nosek, T. M. Related Collections Muscle

¹ Department of Physiology and Biophysics, University of Medicine & Dentistry of New Jersey-Robert Wood Johnson School of Medicine, Piscataway, NJ 08854, USA² Department of Molecular Microbiology & Immunology, Malaria Research Institute, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD 21205, USA³ Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, OH 44106, USA

Although it is well established that patients suffering from malaria experience skeletal muscle problems (contracture, aches, fatigue, weakness), detailed studies have not been performed to investigate changes in the contractile function and biochemical properties of intact and skinned skeletal muscles of mammals infected with malaria. To this end, we investigated such features in the extensor digitorium longus (EDL, fast-twitch, glyocolytic) and in the soleus (SOL, slow-twitch, oxidative) muscles from mice infected with Plasmodium berghei. We first studied maximal tetanic force (T_max) produced by intact control and malaria-infected muscles before, during and after fatigue. Triton-skinned muscle fibres were isolated from these muscles and used to determine isometric contractile features as well as a basic biochemical profile as analysed by silver-enhanced SDS-PAGE. We found that the T_max of intact muscles and the maximal Ca²⁺-activated force (F_max) of Triton-skinned muscle fibres were reduced by 50% in malarial muscles. In addition, the contractile proteins of Triton-skinned muscle fibres from malarial muscles were significantly less sensitive to Ca²⁺. Biochemical analysis revealed that there was a significant loss of essential contractile proteins (e.g. troponins and myosin) in Triton-skinned muscle fibres from malarial muscles as compared to controls. The biochemical alterations (i.e., reduction of essential contractile proteins) seem to explain well the functional modifications resolved in both intact muscles and Triton-skinned muscle fibres and may provide a suitable paradigm for the aetiology of muscle symptoms associated with malaria.

(Received 25 June 2004; accepted after revision 14 February 2005; first published online 22 February 2005)
Corresponding author M. Brotto: Department of Physiology and Biophysics, UMDNJ-Robert Wood Johnson School of Medicine, Piscataway, NJ 08854, USA. Email: brottoma{at}umdnj.edu

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