X-Ray Microanalysis and Free Calcium Measurements in Cultured Neonatal Rat Ventricular Myocytes

The response of cardiac myocytes to changes in calcium homeostasis is thought to be an important factor in cardiac myocyte injury under various conditions of ischemia, hypoxia and reperfusion injury (Allen and Orchard, 1983; Barry et al., 1987; Buja et al., 1985; Farber, 1982; Jennings and Reiner, 1981; Nayler, 1981). During the past several years advances in cryofixation, data collection and interpretation of electron beam excited x-ray microanalysis have been developed in our laboratory (Hagler et al., 1979; Hagler et al., 1983; Hagler and Buja, 1986). The use of x-ray microanalysis techniques have been important in understanding changes in total elemental content on a compartment by compartment and a cell by cell basis (Wendt-Gallitelli and Jacob, 1982; Wendt-Gallitelli and Wolburg, 1984; Wheeler-Clark and Tormey, 1987; Somlyo et al., 1985). A model of hypoxic and ischemic injury in our laboratory has been a primary culture of neonatal rat ventricular myocytes (Buja et al., 1985). Observations will be presented in this paper from this cultured cell model to make general points about biological x-ray microanalysis. The data analysis schemes which we have devised to look at a changing population of cells will be illustrated from this work. We will also present some data on intracellular free calcium measurements and their correlation with x-ray microanalysis measurements in this model.