In:
American Journal of Physiology-Regulatory, Integrative and Comparative Physiology, American Physiological Society, Vol. 275, No. 1 ( 1998-07-01), p. R332-R338
Abstract:
This study explains why the recently described triphasic lipopolysaccharide (LPS) fevers have been repeatedly mistaken for biphasic fevers. Experiments were performed in loosely restrained male Wistar rats with a catheter implanted into the right jugular vein. Each animal was injected with Escherichia coli LPS, and its colonic (T c ) and tail skin temperatures were monitored. The results are presented as time graphs and phase-plane plots; in the latter case the rate of change of T c is plotted against T c . At an ambient temperature (T a ) of 30.0°C, the response to the 10 μg/kg dose of LPS was triphasic, as is obvious from time graphs of T c (3 peaks), time graphs of effector activity (3 waves of tail skin vasoconstriction), and phase-plane plots (3 complete loops). When the T a was below neutral (22.0°C) or the LPS dose was higher (100 or 1,000 μg/kg), the time graph of T c did not allow for the reliable detection of all three febrile phases, but the phase-plane plot and time graph of effector activity clearly revealed the triphasic pattern. In a separate experiment, LPS (10 μg/kg) or saline was injected via one of two different procedures: in the first group the injection was performed through the jugular catheter, from outside the experimental chamber; in the second group the same nonstressing injection was combined with opening the chamber and pricking the animal in its lower abdomen with a needle. In the first group the febrile response was obviously triphasic, and none of the phases was due to the procedure of injection per se (injection of saline did not affect T c ). In the second group the fever similarly consisted of three T c rises, but it might have been readily mistaken for biphasic because the first rise was indistinguishable from stress hyperthermia occurring in the saline-injected (and needle-pricked) controls. We conclude that several methodological factors (dose of LPS, procedure of its injection, and T a ) have contributed, although each in a different way, to the common misbelief that there are only two febrile phases.
Type of Medium:
Online Resource
ISSN:
0363-6119
,
1522-1490
DOI:
10.1152/ajpregu.1998.275.1.R332
Language:
English
Publisher:
American Physiological Society
Publication Date:
1998
detail.hit.zdb_id:
1477297-8
SSG:
12
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