Muscle fibers from senescent mice retain excitatio

Authors: ZhongMin Wang Zhenlin Zheng María L Messi Osvaldo Delbono

Publish Date: 2007/08/22

Volume: 43, Issue: 7, Pages: 222-234

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Abstract

In the present study we test the hypothesis that mouse skeletal muscle in culture retains the fundamental properties of excitationsarcoplasmic reticulum Ca2+ release coupling reported for youngadult 3–4 mo and senescent 22–23 mice Dissociated flexor digitorum brevis FDB muscles from youngadult and senescent mice were cultured for 7 d in a serumfree medium During this period the overall morphology of cultured fibers resembled that exhibited by acutely dissociated cells In addition survival analysis revealed that more than 70 of the fibers from both young and old mice remained suitable for electrophysiological studies during this same culture period Charge movement and intracellular Ca2+ recordings in FDB fibers voltage clamped in the whole cell configuration of the patchclamp technique reproduced the maximal values and voltage dependence similarly displayed by acutely dissociated cells for both parameters in youngadult and senescent mice The analysis of the dihydropyridine receptor by immunoblots confirmed in the culture system the agedependent decrease in the expression of this protein In conclusion FDB fibers from youngadult and old mice retain the excitation–contraction coupling phenotype during the course of a week in serumfree medium cultureThe present study was supported by grants from the National Institutes of Health/National Institute on Aging AG13934 and AG15820 and Muscular Dystrophy Association to Osvaldo Delbono and by the Wake Forest University Claude D Pepper Older Americans Independence Center P30AG21332

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