Lanthanum Probe Studies of Cellular Pathophysiology Induced by Hypoxia in Isolated Cardiac Muscle

Abstract

A C T This study was undertaken to evaluate directly the relationship between evolution of irrevers- ible myocardial injury induced by hypoxia in an iso- lated papillary muscle preparation and the development of pathophysiological alterations related to severely impaired membrane function. An ionic lanthanum probe technique was employed as a cyto- chemical marker to monitor the progression of cellular injury, and data from this cytologic technique were correlated with ultrastructure and measurements of contractile parameters in a total of 67 muscles sub- jected to control conditions or to graded intervals of hypoxia with or without reoxygenation. Marked de- pression of developed tension and rate of tension development occurred after 30 min of hypoxia. Con- tractile function showed significant recovery with reoxygenation after 1 h and 15 min of hypoxia but remained depressed when reoxygenation was provided after 2 or 3 h of hypoxia. Examination by trans- mission and analytical electron microscopy (energy dispersive X-ray microanalysis) revealed lanthanum deposition only in extracellular regions of control muscles and muscles subjected to 30 min of hypoxia. After hypoxic intervals of over 1 h, abnormal intra- cytoplasmic and intramitochondrial localization of lanthanum were detected. After 1 h and 15 min of hypoxia, abnormal intracellular lanthanum accumulation was associated with only minimal ultrastructural Data from this study were presented at the 49th Scientific