Myocardial metabolism during increased work states in the porcine left ventricle in vivo.
Myocardial metabolism during increased work states in the porcine left ventricle in vivo.
复制标题
猪体内左心室工作状态增加时的心肌代谢。
DOI：
10.1161/01.res.74.1.64
复制
发表时间：
1994
影响因子：
20.1
通讯作者：
Owens,T
中科院分区：
文献类型：
--
作者：
Massie,BM;Schwartz,GG;Garcia,J;Wisneski,JA;Weiner,MW;Owens,T
目前尚不清楚在冠状动脉血流或冠状动脉储备不异常的情况下，心肌能量需求是否可以增加到超过心肌O2可用性的程度。为了确定这种形式的“需求缺血”是否发生，10头猪受到由主动脉收缩、多巴酚丁胺的变力性和变时性刺激以及这些干预的组合引起的压力超负荷。在另外9只动物中，在缩窄和多巴酚丁胺的组合期间静脉内施用腺苷，以确定是否可以实现冠状动脉流量的进一步增加以及它们是否会减弱代谢变化。用放射性微球测定左室前壁血流量。能量磷酸盐通过31 P磁共振波谱法使用傅立叶级数窗口技术来评估，以增加来自内膜下的信号的比例。使用同位素示踪技术定量心肌乳酸释放独立于净乳酸摄取。三种干预措施使心肌O2摄取量比对照测量值增加39%至195%。磷酸肌酸与ATP的比值（PCr/ATP），未校正部分饱和，从对照条件下的1.39 +/- 0.10显著下降到单独多巴酚丁胺的1.25 +/- 0.10和多巴酚丁胺加缩窄的1.15 +/- 0.08（两者均P <0.05）。心肌乳酸释放从对照条件下的0.21 +/- 0.03 mumol.g-1.min-1分别增加到0.45 +/- 0.05和0.59 +/- 0.10 mumol.g-1.min-1（两种干预均P <0.05）。尽管左心室的平均血流量从对照条件下的0.97 +/- 0.09 mL.g-1.min-1上升到3.25 +/- 0.47 mL.g-1.min-1，（P <0.001），内膜下血流量从1.02 +/- 0.09增加到2.92 +/- 0.45 mL.g-1.min-1（P < .001）在三种增加的工作状态中最高的，心内膜下与心外膜下血流比从1.13 ± 0.08逐渐下降到0.87 ± 0.04（P <0.05）。随着主动脉收缩的进一步增加，心肌O2摄取和心外膜下血流量上升，而内膜下血流量没有变化，PCr/ATP进一步下降，乳酸释放上升。虽然腺苷使高负荷状态下的平均心肌血流量从3.79 ± 0.91增加到6.29 ± 1.08 mL·g-1·min-1，（P <0.001），内膜下血流从3.08 +/- 0.62进一步升高至3.78 +/- 0.68 mL.g-1.min-1并不显著，PCr/ATP或乳酸代谢也没有伴随变化。（400字处截断摘要）
It is not known whether myocardial energy requirements can be increased to the degree that they exceed myocardial O2 availability in the absence of abnormalities of coronary blood flow or coronary reserve. To determine whether this form of "demand ischemia" occurs, 10 swine were subjected to pressure overload induced by aortic constriction, inotropic and chronotropic stimulation by dobutamine, and the combination of these interventions. In an additional 9 animals, intravenous adenosine was administered during the combination of constriction and dobutamine to determine whether further increases in coronary flow could be achieved and if they would attenuate the metabolic changes. Left ventricular anterior wall transmural blood flow was measured by radioactive microspheres. Energy phosphates were assessed by 31P magnetic resonance spectroscopy using the Fourier series window technique to increase the proportion of signal derived from the subendocardium. Myocardial lactate release was quantified independent of net lactate uptake using an isotopic tracer technique. The three interventions produced 39% to 195% increases in myocardial O2 uptake from control measurements. The phosphocreatine to ATP ratio (PCr/ATP), uncorrected for partial saturation, fell significantly, from 1.39 +/- 0.10 at control conditions to 1.25 +/- 0.10 with dobutamine alone and 1.15 +/- 0.08 with dobutamine plus constriction (P < .05 for both). Myocardial lactate release rose from 0.21 +/- 0.03 mumol.g-1.min-1 at control conditions to 0.45 +/- 0.05 and 0.59 +/- 0.10 mumol.g-1.min-1, respectively (P < .05 for both), with these two interventions. Although transmurally averaged left ventricular blood flow rose from 0.97 +/- 0.09 mL.g-1.min-1 at control conditions to 3.25 +/- 0.47 mL.g-1.min-1 (P < .001) and subendocardial blood flow increased from 1.02 +/- 0.09 to 2.92 +/- 0.45 mL.g-1.min-1 (P < .001) at the highest of the three increased work states, the subendocardial to subepicardial flow ratio declined progressively from 1.13 +/- 0.08 to 0.87 +/- 0.04 (P < .05). With a further increase in aortic constriction, myocardial O2 uptake and subepicardial blood flow rose, whereas subendocardial blood flow did not change, and there was a further decline in PCr/ATP and a rise in lactate release. Although adenosine increased the average myocardial blood flow during high work state from 3.79 +/- 0.91 to 6.29 +/- 1.08 mL.g-1.min-1 (P < .001), the further rise in subendocardial flow from 3.08 +/- 0.62 to 3.78 +/- 0.68 mL.g-1.min-1 was not significant, nor were the accompanying changes in PCr/ATP or lactate metabolism.(ABSTRACT TRUNCATED AT 400 WORDS)