Differentiation of a Myocardial Depressant Factor Present in Shock Plasma from Known Plasma Peptides and Salts 1

Abstract

Summary

Several potent biologically active peptides, some of which are found in mammalian plasma during circulatory shock, were studied for their cardiac and intestinal smooth muscle actions. None of the peptides studied over a concentration range of 10^-9 to 10^-5 M exhibited a biological profile similar to MDF. Moreover, MDF activity could not be accounted for by sodium or by total salts (i.e., osmolality) since a concentration of at least four times normal total salts was required to exert a negative inotropic effect of a comparable magnitude to that induced by plasma concentrations of MDF in shock. Thus, MDF appears to be a small peptide not identifiable with common plasma peptides nor with salts.

All kinin derivatives were kindly supplied by Dr. E. D. Nicholaides of Parke, Davis and Company, Ann Arbor, MI. Bradykinin and eledoisin were generously donated by Sandoz Pharmaceuticals, Hanover, NJ, and angiotensin II by Ciba Pharmaceutical Co., Summit, NJ.