Morphological changes of heart muscle caused by successive perfusion with calcium-free and calcium-containing solutions (calcium paradox)

Abstract

Perfusion of isolated rat hearts with a modified Tyrode solution followed by perfusion with a calcium-free perfusate results in an electromechanical dissociation and causes no significant morphological changes. However, reinstitution of calcium ions leads to gross morphological changes, as shown by histological and electron-microscopical evidence. Contractility is not restored and electrical activity disappears (calcium paradox). Some of the cells are reduced to empty spaces containing swollen mitochondria. Other cells appear to be intact, but show signs of hypercontraction. Cardiac damage due to the calcium paradox could also be demonstrated by x-ray angiography.