Characterization of a myocardial depressant factor present in hemorrhagic shock

Abstract

A substance present in plasma of cats in late hemorrhagic shock which depresses myocardial contractility of isolated cat papillary muscles and which has been termed myocardial depressant factor (MDF) has been further characterized. MDF was found to be dialyzable and therefore of low molecular weight. MDF was not soluble in methylene chloride, all activity being recovered in aqueous extracts. MDF was found to be heat stable, and showed a relatively linear concentration-response relationship. MDF was found not to be hemoglobin, hemochromogen, pyruvate, or lactate. Loss of Ca was not responsible for the myocardial depression seen with MDF. MDF appeared to accumulate in concentrations proportional to the duration of the postoligemic phase of hemorrhagic shock and may play an important role in the pathogenesis of the irreversibility of hemorrhagic shock.