Swain J L, Parker J P, McHale P A, Greenfield J C
J Clin Invest. 1979 May;63(5):947-53. doi: 10.1172/JCI109395.
Chronically instrumented awake dogs were used to study the effects of nitroglycerin and propranolol on the transmural distribution of myocardial blood flow during transient ischemia. Studies were carried out 7-14 d after implantation of an electromagnetic flowmeter probe and balloon occluder on the left circumflex coronary artery, placement of epicardial minor axis sonar crystals, and implantation of left atrial, left ventricular, and aortic catheters. The occluder was inflated to completely interrupt flow for 10 s followed by partial release to reestablish flow at 60% of the preocclusion level. During this partial release, which served as the control for the study, regional myocardial blood flow was measured with 7- to 10-mum radioactive microspheres. After control measurements, seven dogs were given nitroglycerin (0.4 mg i.v.) and eight dogs propranolol (0.2 mg/kg i.v.). 5 min later the occlusion and partial release sequence was repeated, and regional myocardial blood flow was measured when heart rate, aortic and left ventricular end-diastolic pressure, and minor axis diameter were unchanged from control values.The data values were selected so that total flow to the ischemic region during partial release after nitroglycerin or propranolol administration was not significantly different from flow during the control partial release. After nitroglycerin administration, endocardial flow (endo) in the ischemic region increased from 0.46+/-0.07 to 0.59+/-0.06 ml/min per g (P < 0.006); epicardial flow (epi) decreased from 0.78+/-0.09 to 0.70+/-0.08 ml/min per g (P < 0.04). The endo:epi ratio increased from 0.65+/-0.07 to 0.92+/-0.10 (P < 0.05). In contrast, administration of propranolol produced no significant change in transmural flow (endo, 0.42+/-0.02 and 0.46+/-0.03 ml/min per g; epi, 0.71+/-0.06 and 0.70+/-0.07 ml/min per g) or in the endo:epi ratio (0.60+/-0.03, 0.66+/-0.06) in the ischemic region. Nitroglycerin and propranolol produce different effects on the transmural distribution of blood flow to ischemic myocardium. Nitroglycerin can increase blood flow to the underperfused endocardium in the absence of alterations in heart size, hemodynamic parameters, and total transmural flow to the ischemic region. Under similar conditions, propranolol has no significant effect on the transmural distribution of blood flow to an ischemic region.
使用长期植入仪器的清醒犬来研究硝酸甘油和普萘洛尔对短暂缺血期间心肌血流跨壁分布的影响。在电磁流量计探头和左回旋支冠状动脉球囊封堵器植入、心外膜短轴超声晶体放置以及左心房、左心室和主动脉导管植入后7 - 14天进行研究。封堵器充气10秒以完全阻断血流，随后部分释放以将血流重建至封堵前水平的60%。在作为研究对照的此次部分释放期间，用7 - 10μm放射性微球测量局部心肌血流。对照测量后，7只犬静脉注射硝酸甘油（0.4mg），8只犬静脉注射普萘洛尔（0.2mg/kg）。5分钟后重复封堵和部分释放序列，当心率、主动脉和左心室舒张末期压力以及短轴直径与对照值无变化时测量局部心肌血流。选择数据值以使硝酸甘油或普萘洛尔给药后部分释放期间缺血区域的总血流量与对照部分释放期间的血流量无显著差异。给予硝酸甘油后，缺血区域的心内膜血流（endo）从0.46±0.07增加至0.59±0.06ml/min per g（P < 0.006）；心外膜血流（epi）从0.78±0.09减少至0.70±0.08ml/min per g（P < 0.04）。endo:epi比值从0.65±0.07增加至0.92±0.10（P < 0.05）。相比之下，给予普萘洛尔后缺血区域的跨壁血流（endo，0.42±0.02和0.46±0.03ml/min per g；epi，0.71±0.06和0.70±0.07ml/min per g）或endo:epi比值（0.60±0.03，0.66±0.06）无显著变化。硝酸甘油和普萘洛尔对缺血心肌血流的跨壁分布产生不同影响。硝酸甘油可在不改变心脏大小、血流动力学参数以及缺血区域总跨壁血流的情况下增加灌注不足的心内膜血流。在类似条件下，普萘洛尔对缺血区域血流的跨壁分布无显著影响。
