title: Chronic stimulation-induced changes in mitochondria and performance in rat skeletal muscle.
abstract: Chronic low-frequency (10-Hz) electrical stimulation was used to investigate mitochondrial biogenesis in rat tibialis anterior muscle. Succinate dehydrogenase and citrate synthase were used as mitochondrial enzymes, and cardiolipin (CL) was used as a phospholipid index of the inner membrane. Stimulation was via the peroneal nerve (24 h/day) for 1, 2, 3, 5, 7, 10, 14, 21, and 28 days (n = 3-9 rats/day). After each period, endurance performance was evaluated in situ. The contralateral side (CON) served as control nonstimulated muscle. Endurance performance gradually improved after 5 days of stimulation to approximately twofold higher than CON muscle beyond 10 days. Succinate dehydrogenase activity rose to 2.4-fold above CON muscle (4.8 +/- 0.2 U/g; n = 54) by 10 days (half time = 6.1 days) and then remained constant. Citrate synthase demonstrated a similar change. The improved performance with stimulation was correlated (r = 0.61, P < 0.05) to these increases in enzyme activities. CL concentration increased from CON (0.35 +/- 0.02 mumol/g; n = 30) to 3.6- and 3.8-fold above CON at 10 and 14 days (half time = 4.2 days). This increase in CL was greater (P < 0.05) than for either enzyme during the same period. These data are consistent with a model of mitochondrial membrane biogenesis in which enzyme proteins are inserted into a presynthesized lipid bilayer.
authors.affiliation: Department of Physical Education, York University, Ontario, Canada.
authors.forename: M
authors.initials: M
authors.lastname: Takahashi
authors.forename: D A
authors.initials: DA
authors.lastname: Hood
mesh_terms: D000818:Animals; D001794:Blood Pressure / Q000502:physiology; D001834:Body Water / Q000378:metabolism; D002308:Cardiolipins / Q000378:metabolism; D002855:Chromatography, Thin Layer; D002950:Citrate (si)-Synthase / Q000378:metabolism; D004558:Electric Stimulation; D008297:Male; D008931:Mitochondria, Muscle / Q000378:metabolism / Q000502:physiology*; D009119:Muscle Contraction / Q000502:physiology; D009132:Muscles / Q000378:metabolism / Q000502:physiology*; D009929:Organ Size / Q000502:physiology; D010743:Phospholipids / Q000378:metabolism; D010807:Physical Endurance / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D012044:Regression Analysis; D013385:Succinate Dehydrogenase / Q000378:metabolism
chemical_list: D002308:Cardiolipins; D010743:Phospholipids; D013385:Succinate Dehydrogenase; D002950:Citrate (si)-Synthase