Hainsworth R, McGregor K H, Rankin A J, Soladoye A O
J Physiol. 1984 Dec;357:23-35. doi: 10.1113/jphysiol.1984.sp015486.
Experiments were performed on anaesthetized dogs to determine the effects of moderate changes in PCO2 in the cephalic circulation on the inotropic state of the heart and on the reflex inotropic responses from changes in carotid sinus pressure. The cephalic circulation was perfused, through the brachiocephalic and left subclavian arteries, with blood taken from the superior vena cava and equilibrated with various gas mixtures in a gas exchange unit. The carotid sinus regions were vascularly isolated and perfused with arterial blood at controlled pressures. Cardiac inotropic responses were assessed from the maximum rate of change of left ventricular pressure (dP/dtmax) with heart rate and mean aortic pressure held constant. An increase in cephalic blood PCO2 resulted in an increase in dP/dtmax and an increase in the unpaced heart rate. Small, graded changes in cephalic PCO2 resulted in graded responses of dP/dtmax. A change in carotid sinus pressure resulted in a significantly greater response of dP/dtmax when cephalic PCO2 was high. After interruption of the left cardiac sympathetic nerves, the responses of dP/dtmax to changes in cephalic PCO2 and carotid sinus pressure were nearly abolished. These results indicate that the tension of carbon dioxide in the cephalic circulation is likely to be of importance in the control of the inotropic state of the heart. They also imply that, in studies of cardiovascular reflex responses, it is important to control the carbon dioxide tension in the arterial blood.
对麻醉犬进行实验，以确定头循环中PCO2适度变化对心脏变力状态以及颈动脉窦压力变化引起的反射性变力反应的影响。通过头臂动脉和左锁骨下动脉，用上腔静脉采集并在气体交换单元中与各种气体混合物平衡后的血液灌注头循环。将颈动脉窦区域进行血管分离，并在控制压力下用动脉血灌注。在心率和平均主动脉压保持恒定的情况下，根据左心室压力的最大变化率（dP/dtmax）评估心脏变力反应。头循环血液PCO2升高导致dP/dtmax增加和自主心率加快。头循环PCO2的微小、分级变化导致dP/dtmax的分级反应。当头循环PCO2较高时，颈动脉窦压力变化导致dP/dtmax的反应明显更大。切断左心交感神经后，dP/dtmax对头循环PCO2和颈动脉窦压力变化的反应几乎消失。这些结果表明，头循环中二氧化碳张力可能对控制心脏变力状态很重要。它们还意味着，在心血管反射反应的研究中，控制动脉血中二氧化碳张力很重要。
