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349 Acta Physiologica Sinica, August 25, 2010,

62 (4): 349-356 http://www.

actaps.com.cn Research Paper Received 2010-05-11 Accepted 2010-06-24 This work was supported by the Opening Program of Shanghai Key Laboratory of Complex Prescription (No. 10DZ2270900) and the Program of Shanghai Leading Academic Discipline, Shanghai Education Committee, China (No. J50305, J50301). * Corresponding author. Tel: +86-21-51322497;

Fax: +86-21-51322498;

E-mail: [email protected] Transient receptor potentialA1 is involved in cold-induced contraction in the isolated rat colon smooth muscle DONG Yang1,2 , SHIHai-Lian1 , SHI Jian-Rong2 , WU Da-Zheng1,*

1 Institute of Chinese Materia Medica, Shanghai Key Laboratory of Complex Prescription;

2 Experimental Teaching Centre, Shanghai University of Traditional Chinese Medicine, Shanghai 201203, China Abstract: Transient receptor potential (TRP) A1, a member of TRP channel family, is activated by noxious cold. The aims of this study were to determine if TRPA1 contributed to cold-induced contractions in the isolated rat colon preparations and explore the potential mechanisms. The colon smooth muscle layers were surgically isolated from the male Wistar rats and changes in isotonic tension of longitudinal muscle under various treatments were recorded as colonic motilities. Cold stimuli were obtained by the reperfusion with Krebs-Henseleit solution at given temperature using Constant Flow Pump. The mRNA expressions of TRPA1, TRPV1 and TRPM8 in rat colon smooth muscle layer were examined by using reverse transcription-polymerase chain reaction (RT-PCR) techniques. The results showed that the contractions induced by cold stimuli (from

37 °C to

12 °C stepwise) were inversely proportional to the temperature with a maximum contraction at

17 °C in both proximal and distal colons (P