Nandrolone decanoate reduces changes induced by hindlimb suspension in voltage-dependent tension of rat soleus muscle.
The effect of 8 weeks of nandrolone decanoate treatment (15 mg kg(-1)/week, 5 weeks under normal conditions followed by 3 weeks of unloading) was tested for the voltage-dependence of activation and steady-state inactivation of contraction in isolated small bundles (2-4 cells) of intact slow-twitch skeletal muscle in rats. Twenty-four male rats were divided into three groups (8 rats/group, weight matched) for 8 weeks: (1) control, (2) unloaded, and (3) unloaded-treated. Compared with age-matched control values (unloaded vs. control), suspension induced a shift in the isometric tension characteristics toward fast-twitch types in the soleus muscle. In contrast, nandrolone decanoate treatment of suspended animals reduced unweighting-induced atrophy in the muscle and maintained: (1) the relative amplitude of twitch tension to the maximal Ca(2+) activated in saponin-treated fibers (control: 3.6 +/- 0.4%, unloaded: 6.9 +/- 1.1% and unloaded-treated: 4.6 +/- 0.2%), (2) the time to peak tension (control: 130 +/- 18 ms, unloaded: 85 +/- 12 ms and unloaded-treated: 110 +/- 11 ms), (3) the time constant of relaxation (control: 320 +/- 12 ms, unloaded: 120 +/- 13 ms and unloaded-treated: 349 +/- 20 ms), (4) the relative amplitude of K(+) contracture tension to the maximal Ca(2+) activated in saponin-treated fibers (control: 82.9 +/- 3.1%, unloaded: 65.1 +/- 2.8%, and unloaded-treated: 91.7 +/- 1.9%), (5) the potential at 50% of the activation curve (control: -40.4 +/- 1.2 mV, unloaded: -35.5 +/- 1.6 mV, and unloaded-treated: -48.4 +/- 1.2 mV), and (6) the potential at 50% of the inactivation curve (control: 42.2 +/- 1.9 mV, unloaded: -34.5 +/- 1.1 mV, and unloaded-treated: -37.9 +/- 1.1 mV). This study clearly shows that treatment with anabolic-androgenic steroids can prevent atrophy and functional changes induced by 3 weeks of unweighting in rat skeletal muscles.
Bouhlel
Aicha
A
Laboratoire de Physiologie Générale, CNRS UMR 6018, Faculté des Sciences et des Techniques, Université de Nantes, 2 rue de la Houssinière, B.P. 92208, 44322 Nantes Cedex 3, France.
Joumaa
Wissam H
WH
Léoty
Claude
C
D000818:Animals; D001835:Body Weight; D002118:Calcium / Q000494:pharmacology; D004558:Electric Stimulation; D019417:Hindlimb Suspension / Q000502:physiology*; D007700:Kinetics; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects; D009119:Muscle Contraction / Q000187:drug effects*; D018656:Muscle Fibers, Fast-Twitch / Q000502:physiology; D018657:Muscle Fibers, Slow-Twitch / Q000502:physiology; D009126:Muscle Relaxation / Q000187:drug effects; D018482:Muscle, Skeletal / Q000187:drug effects* / Q000502:physiology; D009277:Nandrolone / Q000031:analogs & derivatives* / Q000494:pharmacology*; D000077603:Nandrolone Decanoate; D011189:Potassium Chloride / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D012503:Saponins / Q000494:pharmacology
D012503:Saponins; D011189:Potassium Chloride; D009277:Nandrolone; D000077603:Nandrolone Decanoate; D002118:Calcium