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MUSCLE CELL BIOLOGY AND CELL MOTILITY
Departments of 1Regulatory Cell Physiology and 2Forensic Medical Science, Nagoya City University Graduate School of Medical Sciences, Mizuho-ku, Nagoya 467-8601, Japan
Submitted 11 September 2003 ; accepted in final form 23 December 2003
We studied whether acetaldehyde, which is produced by alcohol consumption, impacts ryanodine receptor (RyR) activity and muscle force. Exposure to
50200 µM acetaldehyde enhanced channel activity of frog RyR and rabbit RyR1 incorporated into lipid bilayers. An increase in acetaldehyde to 1 mM modified channel activity in a time-dependent manner, with a brief activation and then inhibition. Application of 200 µM acetaldehyde to frog fibers increased twitch tension. The maximum rate of rise of tetanus tension was accelerated to 1.5 and 1.74 times the control rate on exposure of fibers to 50 and 200 µM acetaldehyde, respectively. Fluorescence monitoring with fluo 3 demonstrated that 200400 µM acetaldehyde induced Ca2+ release from the sarcoplasmic reticulum (SR) in frog muscles. Acetaldehyde at 1 mM inhibited twitch tension by
12%, with an increased relaxation time after a small, transient twitch potentiation. These results suggest that moderate concentrations of acetaldehyde can elicit Ca2+ release from the SR by increasing the open probability of the RyR channel, resulting in increased tension. However, the effects of acetaldehyde at clinical doses (130 µM) are unlikely to mediate alcohol-induced acute muscle dysfunction.
ryanodine receptor; single-channel current; fluo 3 fluorescence; calcium ion release; calcium ion uptake
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