SERRATIA MARCESCENS ENDOTOXIN SHOCK.

The effect of crude Serratia marcescens endotoxin on the physiological behavior of the dog was studied. Dogs administered crude S. marcescens endotoxin experienced an initial hypotension, partial recovery, and a secondary terminal fall in blood pressure similar to that previously described for Escherichia coli endotoxin shock. Animals in this study, however, died primarily of respiratory failure rather than cardiovascular collapse. Evisceration eliminated only the initial fall in blood pressure. Artificial ventilation at time of respiratory arrest extended time to death, but all animals subsequently expired with signs of respiratory collapse. The phrenic nerve, the neuromuscular junction, and the diaphragm appeared to be relatively unaffected by the endotoxin, indicating that respiratory failure probably occurs in the central nervous system. Temporary respiration was restored by Metrazol however, all animals expired. Crude S. marcescens endotoxin may have two independent actions--one on the central respiratory mechanism and another on the cardiovascular system. The various fractions are being correlated with pharmacological activity in current studies. Author