Bussemaker J, van Beek J H, Groeneveld A B, Hennekes M, Teerlink T, Thijs L G, Westerhof N
Laboratory for Physiology, Free University, Amsterdam, The Netherlands.
J Mol Cell Cardiol. 1994 Aug;26(8):1017-28. doi: 10.1006/jmcc.1994.1122.
To study whether heterogeneous myocardial blood flow relates to the local oxidative capacity of cardiac muscle, local blood flow at resting cardiac workloads and the activity of the mitochondrial enzyme succinate dehydrogenase (SDH) were determined in small regions of the left ventricle of seven anaesthetized, mechanically ventilated, open-chest pigs (25-35 kg). Following injection of radioactive microspheres (15 microns phi) into the left atrium, the heart was rapidly excised and cut into five transverse slices, which were simultaneously freeze-clamped between two aluminum blocks precooled at -80 degrees C. The left ventricle was then subdivided into 84 samples of about 0.9 g. Myocardial blood flow was 0.88 +/- 0.34 ml/min/g wet weight (ww), and SDH activity 1.46 +/- 0.33 mumol/min/g ww (mean +/- S.D., n = 7). Local data were normalized to their respective mean values in each pig, and then pooled. Local blood flow ranged from 0.32 to 1.63 of the mean, and blood flow heterogeneity characterized by the coefficient of variation (CV = S.D./mean) was 18.4%. Normalized local SDH activity ranged from 0.16 to 1.94, with a CV of 21.8%, significantly exceeding measurement error (CV = 4.5%). Local blood flows and SDH activities did not vary among transmural sublayers of the left ventricle, but variation within each sublayer was considerable. In six of the seven pigs, local blood flow correlated (P < 0.05) with SDH activity, with correlation coefficients (r) ranging from 0.26 to 0.54 (for pooled data: r = 0.27, P < 0.0001). When expressed per gram dry weight, heterogeneity of SDH activity increased (P < 0.05), and here also local blood flow correlated with SDH activity in all pigs (for pooled data: r = 0.45, P < 0.0001). Hence, heterogeneity of mitochondrial capacity within cardiac muscle partly explains the heterogeneity of myocardial blood flow, even though myocardial perfusion at rest was studied in relation with a maximal enzyme rate. The low correlation coefficient clearly indicates that at resting workloads other factors also play a role.
为研究心肌血流不均一性是否与心肌局部氧化能力相关，对7只麻醉、机械通气、开胸的猪（25 - 35千克）左心室的小区域测定了静息心脏负荷下的局部血流以及线粒体酶琥珀酸脱氢酶（SDH）的活性。向左心房注射放射性微球（直径15微米）后，迅速切除心脏并切成5个横向切片，同时在预冷至 -80℃的两个铝块之间进行冷冻钳夹。然后将左心室再细分为约0.9克的84个样本。心肌血流为0.88±0.34毫升/分钟/克湿重（ww），SDH活性为1.46±0.33微摩尔/分钟/克湿重（均值±标准差，n = 7）。将局部数据归一化为每只猪各自的均值，然后合并。局部血流范围为均值的0.32至1.63，以变异系数（CV = 标准差/均值）表征的血流不均一性为18.4%。归一化的局部SDH活性范围为0.16至1.94，CV为21.8%，显著超过测量误差（CV = 4.5%）。左心室跨壁各亚层之间的局部血流和SDH活性无差异，但各亚层内的差异相当大。在7只猪中的6只，局部血流与SDH活性相关（P < 0.05），相关系数（r）范围为0.26至0.54（合并数据：r = 0.27，P < 0.0001）。当以每克干重表示时，SDH活性的不均一性增加（P < 0.05），并且在所有猪中局部血流也与SDH活性相关（合并数据：r = 0.45，P < 0.0001）。因此，心肌内线粒体容量的不均一性部分解释了心肌血流的不均一性，尽管研究的是静息心肌灌注与最大酶活性速率的关系。低相关系数清楚地表明在静息负荷下其他因素也起作用。
