PERMEABILITY OF MUSCLE CAPILLARIES TO EXOGENOUS MYOGLOBIN

Whale skeletal muscle myoglobin (mol wt 17,800; molecular dimensions 25 x 34 x 42 Å) was used as a probe molecule for the pore systems of muscle capillaries. Diaphragms of Wistar-Furth rats were fixed in situ at intervals up to 4 h after the intravenous injection of the tracer, and myoglobin was localized in the tissue by a peroxidase reaction. Gel filtration of plasma samples proved that myoglobin molecules remained in circulation in native monomeric form. At 30–35 s postinjection, the tracer marked ~75% of the plasmalemmal vesicles on the blood front of the endothelium, 15% of those located inside and none of those on the tissue front. At 45 s, the labeling of vesicles in the inner group reached 60% but remained nil for those on the tissue front. Marked vesicles appeared on the latter past 45 s and their frequency increased to ~80% by 60–75 s, concomitantly with the appearance of myoglobin in the pericapillary spaces. Significant regional heterogeneity in initial labeling was found in the different segments of the endothelium (i.e., perinuclear cytoplasm, organelle region, cell periphery, and parajunctional zone). Up to 60 s, the intercellular junctions and spaces of the endothelium were free of myoglobin reaction product; thereafter, the latter was detected in the distal part of the intercellular spaces in concentration generally equal to or lower than that prevailing in the adjacent pericapillary space. The findings indicate that myoglobin molecules cross the endothelium of muscle capillaries primarily via plasmalemmal vesicles. Since a molecule of this size is supposed to exit through both pore systems, our results confirm the earlier conclusion that the plasmalemmal vesicles represent the large pore system; in addition, they suggest that the same structures are, at least in part, the structural equivalent of the small pore system of this type of capillaries.     

冠心病猝死心肌肌红蛋白缺失的免疫组化进一步研究

目的探讨冠脉狭窄程度与心肌肌红蛋白缺失的关系及心肌肌红蛋白缺失在冠心病猝死中的意义和诊断价值.方法综合应用常规病理学方法、免疫组化技术(SABC法)和图像分析处理系统,对本教研室26例冠心病猝死病例和17例非冠心病猝死的对照组病例的心肌肌红蛋白缺失情况进行对比研究.结果冠心病猝死者心肌内均有肌红蛋白缺失,呈多发散在灶片状分布,且冠脉狭窄最严重处相应部位心肌的肌红蛋白缺失较其他部位更明显,而对照组无或仅见轻度缺失.用SAS统计软件包对图像分析结果进行统计处理发现有显著性差异.结论心肌的肌红蛋白缺失情况可用作冠心病猝死的诊断指标之一.