迷走神经与乙酰胆碱对缩窄的犬冠状动脉节段阻力的影响

在麻醉开胸犬,用电起搏维持心率恒定,研究了电刺激颈迷走神经(VNS)及冠状动脉内注入乙酰胆碱(ACh)对缩窄的冠状动脉的节段阻力及血流量的影响。在左旋支主干造成不同程度的冠状动脉缩窄。分别测定左旋支血流量(CBF_(cx))、主动脉压和主旋支远端冠状动脉压,记录心电图。实验发现,在冠状动脉临界狭窄和重度狭窄时,VNS 或冠脉给ACh 引起心外膜大冠状动脉阻力及冠状动脉主旋支总阻力增大,CBF_(cx)减少;随着缩窄程度加重,这些改变也愈明显,然而,心肌内小冠状动脉阻力却无显著改变。

THE EFFECT OF VAGUS AND ACETYLCHOLINE ON SEGMENTAL CORONARY RESISTANCE IN THE PRESENCE OF CORONARY ARTERIAL STENOSIS IN THE DOG

In anesthetized open-chest dogs with the hearts being paced at a constant rate,we studied the effect of electrical stimulation of cervical vagal nerve (VNS) or in-tracoronary infusion of acetylcholine (ACh) on circumflex coronary blood flow(CBFcx) and segmental coronary arterial resistance in the presence of gradedcoronary stenosis. CBFcx was measured with electromagnetic flowmeter. Aorticpressure, distal circumflex branch pressure and heart rate were also measured.The experimental results showed that VNS or intracoronary ACh caused epicardiallarge coronary arterial resistance and total resistance of the circumflex branch (R_T)to increase and CBFcx to decrease under the conditions of critical or severe coronarystenosis. And the severer coronary arterial stenosis was, the more obviously R_Tincreased and CBFcx decreased. However, myocardial small coronary arterialresistance did not change markedly.