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首页> 外文期刊>American Journal of Physiology >Reduced oxygen supply explains the negative force-frequency relation and the positive inotropic effect of adenosine in buffer-perfused hearts.
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Reduced oxygen supply explains the negative force-frequency relation and the positive inotropic effect of adenosine in buffer-perfused hearts.

机译：氧气供应减少解释了在缓冲液灌注的心脏中，腺苷的负频率关系和正性肌力作用。

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摘要

In isolated rat hearts perfused with HEPES and red blood cell-enriched buffers, we examined changes in left ventricular pressure induced by increases in heart rate or infusion of adenosine to investigate whether the negative force-frequency relation and the positive inotropic effect of adenosine are related to an inadequate oxygen supply provided by crystalloid perfusates. Hearts perfused with HEPES buffer at a constant flow demonstrated a negative force-frequency relation, whereas hearts perfused with red blood cell-enriched buffer exhibited a positive force-frequency relation. In contrast, HEPES buffer-perfused hearts showed a concentration-dependent increase in left ventricular systolic pressure [EC50 = 7.0 +/- 1.2 nM, maximal effect (Emax) = 104 +/- 2 and 84 +/- 2 mmHg at 0.1 microM and baseline, respectively] in response to adenosine, whereas hearts perfused with red blood cell-enriched buffer showed no change in left ventricular pressure. The positive inotropic effect of adenosine correlated withthe simultaneous reduction in heart rate (r = 0.67, P < 0.01; EC50 = 3.8 +/- 1.4 nM, baseline 228 +/- 21 beats/min to a minimum of 183 +/- 22 beats/min at 0.1 microM) and was abolished in isolated hearts paced to suppress the adenosine-induced bradycardia. In conclusion, these results indicate that the negative force-frequency relation and the positive inotropic effect of adenosine in the isolated rat heart are related to myocardial hypoxia, rather than functional peculiarities of the rat heart.
机译：在灌注了HEPES和富含红细胞的缓冲液的离体大鼠心脏中，我们检查了心率增加或腺苷输注引起的左心室压力变化，以研究腺苷的负力频率关系和正性肌力作用是否相关晶体灌注液提供的氧气供应不足。以恒定流量灌注HEPES缓冲液的心脏表现出负的力频率关系，而以富含红细胞的缓冲液灌注的心脏表现出正的力频率关系。相比之下，HEPES缓冲液灌注的心脏显示出左室收缩压的浓度依赖性升高[EC50 = 7.0 +/- 1.2 nM，最大效应（Emax）= 104 +/- 2和84 +/- 2 mmHg（0.1 microM）和基线]分别响应腺苷，而灌注了富含红细胞的缓冲液灌注的心脏显示左心室压力无变化。腺苷的正性肌力作用与同时降低心率相关（r = 0.67，P <0.01; EC50 = 3.8 +/- 1.4 nM，基线228 +/- 21拍/分钟，最低183 +/- 22拍/ min（0.1 microM / min），并在孤立的心脏中取消，以抑制腺苷引起的心动过缓。总之，这些结果表明，离体大鼠心脏中腺苷的负频率频率关系和正性肌力作用与心肌缺氧有关，而不是与大鼠心脏的功能特性有关。

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