Grover G J, Scholz P, Mackenzie J W, Weiss H R
Department of Physiology, University of Medicine and Dentistry of New Jersey, Robert Wood Johnson Medical School, Piscataway 08854-5635.
J Cardiovasc Pharmacol. 1988 Apr;11(4):396-401. doi: 10.1097/00005344-198804000-00003.
The effect of intravenous (i.v.) nifedipine (5 micrograms/kg/min) on regional O2 supply/consumption variables was determined in 14 anesthetized open-chest dogs subjected to left anterior descending coronary artery (LAD) stenosis sufficient to reduce blood flow 50%. Myocardial blood flow was measured using radioactive microspheres, and regional arterial and venous O2 saturations were determined using microspectrophotometry. During LAD occlusion, blood flow and O2 consumption were decreased in the ischemic region while O2 extraction was increased. With nifedipine treatment, LAD flow (flow probe) was increased 44% as compared with the initial occluded value, with most of this increase going to the subepicardium (microspheres). Flow to the ischemic subendocardium was not changed with nifedipine treatment. Ischemic subepicardial O2 consumption increased slightly in nifedipine-treated animals as compared with saline values, whereas O2 extraction decreased slightly. In the subendocardial region, nifedipine resulted in a significant decrease in O2 extraction, with a slight decrease in O2 consumption as compared with saline controls. The O2 supply/demand ratio was significantly improved with nifedipine only in the subendocardium of the ischemic region. This suggested that nifedipine could increase O2 consumption in the ischemic subepicardium through proportional increase in O2 supply while it decreased O2 consumption in the subendocardium relative to O2 supply.
在14只麻醉开胸犬身上，测定了静脉注射硝苯地平（5微克/千克/分钟）对局部氧供/氧耗变量的影响，这些犬的左前降支冠状动脉（LAD）狭窄程度足以使血流量减少50%。使用放射性微球测量心肌血流量，并用显微分光光度法测定局部动脉和静脉血氧饱和度。在LAD闭塞期间，缺血区域的血流量和氧耗降低，而氧摄取增加。硝苯地平治疗后，与初始闭塞值相比，LAD血流量（流量探头）增加了44%，其中大部分增加流向心外膜下区域（微球）。硝苯地平治疗后，缺血性心内膜下区域的血流量未发生变化。与生理盐水组相比，硝苯地平治疗的动物缺血性心外膜下氧耗略有增加，而氧摄取略有下降。在心内膜下区域，硝苯地平导致氧摄取显著降低，与生理盐水对照组相比，氧耗略有下降。硝苯地平仅在缺血区域的心内膜下显著改善了氧供/氧需比。这表明硝苯地平可通过按比例增加氧供来增加缺血性心外膜下的氧耗，同时相对于氧供降低心内膜下的氧耗。
