Journal of Applied Physiology, Vol 50, Issue 1 185-190, Copyright © 1981 by American Physiological Society
Effect of methysergide on the acute lung mechanics response to endotoxin
R. C. Allison, T. L. Murphy, I. M. Weisman, D. R. McCaffree and B. A. Gray
The effect of the serotonin antagonist methysergide on the acute lung
mechanics response to endotoxin in anesthetized, paralyzed, mechanically
ventilated dogs was investigated. In five dogs given 0.25 mg/kg Escherichia
coli endotoxin only, the pulmonary nonelastic resistance (RL) increased to
238% of control and dynamic compliance (CL) decreased to 50% of control. In
a second group of five dogs, methysergide (0.25 mg/kg) was shown to
markedly attenuate the lung mechanics response to serotonin (0.04 mg/kg),
which alone had produced changes in lung mechanics greater than endotoxin.
In these same dogs endotoxin administered after injection of methysergide
produced an increase in RL to 377% and a decrease in CL to 33% of control.
In a third group of five dogs whose lung mechanics response to serotonin
was also greater than to endotoxin alone, endotoxin administered after
injection of saline produced an increase in RL to 168% and a decrease in CL
to 58% of control. Since the response to endotoxin after injection of
methysergide exceeded the response after saline, we conclude that serotonin
is not a mediator of the acute lung mechanics response to endotoxin.
