Quantitative assessment of a circulating depolarizing factor in shock

Sustained depolarization of cell membranes and cellular edema are known to accompany various forms of circulatory shock and probably contribute to hyp ovolemia and cellular dysfunction. It has been proposed that a circulating protein is responsible for these effects. In the present study we have conf irmed the existence of a circulating depolarizing factor (CDF) in hemorrhag ic shock, burn shock, sepsis, and cardiopulmonary bypass. Plasma samples fr om pigs or sheep in shock were quantitatively assayed for depolarizing acti vity using a microelectrode method on rat diaphragm in vitro. The depolariz ing effect of CDF in vitro was similar in magnitude to that of shock in sit u. We conclude that CDF can entirely account for membrane depolarization du ring shock. The depolarizing effect of CDF was dose-dependent and saturable ; it could be reversed by rinsing the diaphragm with Ringer's or control pl asma. CDF activity was detectable in plasma within 5 min after a severe sca ld and gradually increased over the next 25 min. Resuscitation of hemorrhag ed pigs, but not burned sheep, eliminated plasma CDF activity.