Issue Archive

Dependence of ventricular wallstress induced refractoriness changes on pacing cycle lengths and its mechanism

WANG Ring- Mang, CHENG Long- Ma, CHEN Juir Zhu, ZHOU Li-Long, ZGUO Xiao- Gang, SHANG YunPen

Cardiovascular Disease Department First Hospital Affiliated to Wical College of Zhejiang Universitylar Disease Department , Union Hospital Affiliated to Tongji Medical College Huazhong University Science and Technology，Wuhan 430022

Abstract

The aim of this article was to investigate the dependence of ventricular wallstress-induced refractoriness changes on pacing cycle lengths and its mechanism in anaesthetized rabbits .The rabbit heart preparation
was use d .The left ventricular afterload was increased by partially clipping the root of the ascending aorta .The changes in effective refractory periods(ERP) induced妙the left ventricular afterload rising were examined at dif-
ferent pacing cycle lengths(1 000，500，300 and 200 ms).In addition，the effect of streptomycin on these changes was also observed .The results are as follows:(1)The rising of left ventricular afterload led to marked
changes in ERP at rapidly pacing cycle lengths(300 ms，21士5 ms，17.0;200 ms，19士3 ms，18.8.P <0.01)than at slow ones(1 000 ms，3士2 ms，1 .5;500 ms，7士3 ms，4.0.P>0.05);(2) Streptomycin inhibited the changes caused by the left ventricular afterload rising at pacing cycle lengths 300 ms and 200
ms(P>0.05).It is suggested that ventricular wallstress-induced refractoriness changes are pacing cycle lengthdependent，and the effect of streptomycin appears to be consistent with the inhibition of stretch-activated ion
channels.

Key words: repfractoiy period;streptomycin;mechano-electric feedback;rabbit

Received: 　　Accepted:

Corresponding author: 　　E-mail:

Citing This Article：

WANG Ring- Mang, CHENG Long- Ma, CHEN Juir Zhu, ZHOU Li-Long, ZGUO Xiao- Gang, SHANG YunPen. Dependence of ventricular wallstress induced refractoriness changes on pacing cycle lengths and its mechanism. Acta Physiol Sin 2003; 55 (3): (in Chinese with English abstract).