MORPHOMETRIC EVALUATION OF VOLUME SHIFTS BETWEEN INTRACELLULAR AND EXTRACELLULAR-SPACES BEFORE AND DURING GLOBAL-ISCHEMIA

Background: It is well known that all forms of cardiac arrest lead to global ischemia combined with alterations in cellular and interstitial volume. The aim of this study was to investigate the nature of these alterations with respect to different methods of cardiac arrest and es tablish the extent of their mutual influence at the onset as well as d uring the course of global ischemia. Methods: Three tested clinical me thods were employed to induce cardiac arrest by a) aortic cross clampi ng, b) coronary perfusion with the cardioplegic solution St. Thomas, a nd c) coronary perfusion with the cardioplegic solution histidine-tryp tophane-ketoglutarate (HTK). The arrested hearts were subjected to glo bal ischemia at 25 degrees C. The size of the myocytes, as well as the interstitial space of myocytes, was determined morphemetrically. The contraction state of myocytes was evaluated according to a score. Resu lts: We found that the degree of contraction, as well as nature of alt erations in the cellular and interstitial volumes, depended both on th e form of cardiac arrest and on the duration of ischemia. The followin g relationships were established. High contraction at the onset of isc hemia leads to expulsion of fluid from the interstitium between bundle s of myocytes into the tissue clefts increasing their size. The decrea se in contraction during ischemia leads to narrower tissue clefts. Cel lular swelling at the onset of and during ischemia is caused by volume shifts between intracellular and interstitial space. An increase in c ellular volume during global ischemia and/or additional contraction re duce the interstitium within bundles of myocytes. Sufficient relaxatio n and/or interstitial edema enlarge the interstitium. Conclusions: Cel lular and interstitial alterations seen at the onset and during the co urse of ischemia are dependent upon the method of cardiac arrest, Furt hermore, a considerable mutual influence is exerted by the alterations in cellular and interstitial spaces. (C) 1995 Wiley-Liss, Inc.