A new linearly-combined bi-exponential model for kinetic analysis of the isometric relaxation process of Bufo gastrocnemius under electric stimulation in vitro

作     者：GUO Rui LI Sheng-bing ZHAO Li-na ZHAO Yun-sheng LU Wei YUAN Pei DENG Ping LIAO Fei 

作者机构：Unit of Biochemical Pharmacology and Protein Biotechnology Chongqing Key Laboratory of Biochemistry and Moleczdar Pharmacology College of Pharmaceutical Sciences Chongqing Medical University Chongqing 400016 China 

出 版 物：《Journal of Zhejiang University-Science B(Biomedicine & Biotechnology)》 (浙江大学学报（英文版）B辑（生物医学与生物技术）)

年 卷 期：2007年第8卷第12期

页      面：867-874页

核心收录：

学科分类：0710[理学-生物学] 1007[医学-药学(可授医学、理学学位)] 1006[医学-中西医结合] 100706[医学-药理学] 07[理学] 071003[理学-生理学] 100602[医学-中西医结合临床] 10[医学] 

基　　金：Project supported by the National Natural Science Foundation of China (No. 30472139) the Education Commission for the First Batch of Excellent Young Teachers in Universities of Chongqing City, China 

主　　题：Bufo gastrocnemius Ca^2+ -pump Cyclopiazonic acid (CPA) Linearly-combined bi-exponential model Muscle relaxation rate Residual distribution Rest tension 

摘      要：There was a slow-relaxing tail of skeletal muscles in vitro upon the inhibition of Ca2+-pump by cyclopiazonic acid (CPA). Herein, a new linearly-combined bi-exponential model to resolve this slow-relaxing tail from the fast-relaxing phase was investigated for kinetic analysis of the isometric relaxation process of Bufo gastrocnemius in vitro, in comparison to the single exponential model and the classical bi-exponential model. During repetitive stimulations at a 2-s interval by square pulses of a 2-ms duration at 12 V direct currency (DC), the isometric tension of Bufo gastrocnemius was recorded at 100 Hz. The relaxation curve with tensions falling from 90% of the peak to the 15th datum before next stimulation was analyzed by three exponential models using a program in MATLAB 6.5. Both the goodness of fit and the distribution of the residuals for the best fitting sup- ported the comparable validity of this new bi-exponential model for kinetic analysis of the relaxation process of the control muscles. After CPA treatment, however, this new bi-exponential model showed an obvious statistical superiority for kinetic analysis of the muscle relaxation process, and it gave the estimated rest tension consistent to that by experimentation, whereas both the classical bi-exponential model and the single exponential model gave biased rest tensions. Moreover, after the treatment of muscles by CPA, both the single exponential model and the classical bi-exponential model yielded lowered relaxation rates, nevertheless, this new bi-exponential model had relaxation rates of negligible changes except much higher rest tensions. These results suggest that this novel linearly-combined bi-exponential model is desirable for kinetic analysis of the relaxation process of muscles with altered Ca2+-pumping activity.