Brack Kieran E, Coote John H, Ng G André
Department of Physiology, Division of Medical Sciences, University of Birmingham, Medical School, Vincent Drive, Edgbaston, Birmingham, B15 2TT, UK.
Auton Neurosci. 2006 Jan 30;124(1-2):69-80. doi: 10.1016/j.autneu.2005.11.005. Epub 2006 Feb 7.
The relative contribution of the chronotropic effects of stimulating sympathetic and vagus nerves on cardiac inotropic changes in the isolated Langendorff perfused rabbit heart with intact dual autonomic nerves was studied. The force-frequency relationship was investigated, in addition to sympathetic nerve stimulation (SS) at 2 Hz (low), 5 Hz (med) and 10 Hz (high), and left and right vagus nerve stimulation (VS) studied at 2 Hz (low), 5 Hz (med) and 7 Hz (high) with and without right ventricular pacing. It was shown that a biphasic force-frequency relationship is present with a positive relationship at low heart rates and a negative force-frequency relationship at higher heart rates. There was a trend for left- and right-VS to decrease left ventricular pressure with a decrease in heart rate, whilst SS had the opposing effects in a frequency-dependent manner. When heart rate was kept constant, there was no effect from left- or right-VS, while SS increased left ventricular pressure in a frequency-dependent manner. Together these results suggest that SS, left- and right-VS alter left ventricular force by two different mechanisms. Left- and right-VS decrease left ventricular pressure predominantly via chronotropic effects whilst SS increases force predominantly by direct changes in contractility.
研究了在具有完整双重自主神经的离体Langendorff灌注兔心脏中，刺激交感神经和迷走神经的变时效应对心脏变力性变化的相对贡献。除了以2Hz（低）、5Hz（中）和10Hz（高）刺激交感神经（SS），以及在有和没有右心室起搏的情况下，分别以2Hz（低）、5Hz（中）和7Hz（高）刺激左、右迷走神经（VS）外，还研究了力-频率关系。结果表明，存在双相力-频率关系，在低心率时呈正相关，在高心率时呈负相关。左、右VS有使左心室压力随心率降低而下降的趋势，而SS则以频率依赖性方式产生相反的作用。当心率保持恒定时，左、右VS无作用，而SS以频率依赖性方式增加左心室压力。这些结果共同表明，SS、左VS和右VS通过两种不同机制改变左心室力。左、右VS主要通过变时效应降低左心室压力，而SS主要通过收缩性的直接变化增加力。
