[Rest tension-based characterization of isometric contractility of Bufo gastrocnemius ex vivo].
OBJECTIVE
To characterize the isometric contractility of Bufo gastrocnemius ex vivo in light of the rest tension.


METHODS
Bufo gastrocnemius treated with SOD inhibitor and ascorbate was stimulated electrically (12 V DC, 2 ms duration with a 2 s interval) to record the tension within 10 min. Weighted fitting to the relaxation curve of the tension below 90% of the peak tension with a mono-exponential model yielded the rest tension and relaxation rate.


RESULTS
The control gastrocnemius showed monotonic decrease of the rest tension, but treatment with SOD inhibitor and ascorbate resulted in a decrease of the rest tension followed by a fast increase within a 1.0 min contraction. The increase of the rest tension at 7.0 min of contraction of the treated muscle was significantly greater than that of the control muscle. The control muscle showed a monotonic decrease of the relaxation rate in 10 min, whereas treatment with SOD inhibitor and ascorbate produced increased relaxation rate followed by monotonic decrease till a plateau was reached. In the course of the 10 min recording, the relaxation rate of the treated muscle was lower than that of the control after the same duration of contraction.


CONCLUSIONS
Rest tension is a characteristic index to represent the skeletal muscle contractility.
Liao
Fei
F
Laboratory of Bioinformatics and Molecular Engineering, Chongqing Key Laboratory of Biochemistry and Molecular Pharmacology, College of Pharmaceutical Sciences, Chongqing Medical University, Chongqing, China. liaofeish@yahoo.com
Guo
Rui
R
Li
Sheng-bing
SB
Zuo
Yu-ping
YP
Lu
Jie
J
Sun
An-ping
AP