AJP - Regulatory, Integrative and Comparative Physiology, Vol 251, Issue 1 41-R47, Copyright © 1986 by American Physiological Society
Dehydration enhances endotoxin fever by increased production of endogenous pyrogen
A. Morimoto, N. Murakami, T. Ono and T. Watanabe
The febrile responses in rats to an intravenous injection of the bacterial
endotoxin Salmonella typhosa were investigated under normally hydrated and
dehydrated conditions. When endotoxin was injected intravenously into the
dehydrated rats, a biphasic-patterned fever resulted, whereas in normal
rats an intravenous injection of endotoxin did not induce fever. No
significant differences in febrile responses to the intravenous endogenous
pyrogen (EP), prostaglandin E2, and intracerebroventricular prostaglandin
E2 between normal and dehydrated rats were observed. When the blood plasma
obtained from rats with endotoxin-induced fever under dehydrated conditions
was transferred to the normal rats, a significant rise in the body
temperature was induced. The effect of hydration by an administration of
the hypotonic solution after dehydration was examined in endotoxin-induced
fever and in changes of the basic blood parameters. It is concluded that
febrile responses to endotoxin during dehydrated condition are caused by an
increased production of EP. The migration of leukocytes from circulation to
any other tissue will be an important factor in producing EP under
dehydrated conditions. Furthermore, under dehydrated condition, EP may be
produced by numerous macrophages in tissues in vivo, where many kinds of
leukocytes migrate and exchange signals with each other in developing an
immune response.
