AJP - Heart and Circulatory Physiology, Vol 242, Issue 2 203-H210, Copyright © 1982 by American Physiological Society
Dissociation of Ca2+ accumulation from protein release in calcium paradox: effect of barium
W. G. Nayler and P. M. Grinwald
Experiments were undertaken to establish whether Ba2+ can substitute for
Ca2+ in maintaining the structural and functional integrity of the
glycocalyx. Adult rat hearts were perfused with Ca2+-free buffer at 37
degrees C, with and without added Ba2+. Ten minutes later Ba2+-free,
Ca-containing medium was reintroduced. Hearts that had been perfused with
Ca2+-free medium exhibited a distorted glycocalyx. On reperfusion with
Ca2+-containing medium these hearts released protein (P less than 0.001),
gained Ca2+ (P less than 0.001), and depleted their tissue stores of ATP (P
less than 0.001) and CP (P less than 0.001). Hearts that had been perfused
with Ca2+-free, Ba2+-containing medium retained an apparently intact
glycocalyx. On reperfusion with Ca2+-containing. Ba2+-free medium they
gained Ca2+ but did not lose protein. These results suggest that Ba2+ only
partially replaces Ca2+ in maintaining the integrity of the cell surface.
It is also concluded that the absence of protein release does not
necessarily exclude the occurrence of severe changes in ionic permeability
after cell injury.
