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Plasma catecholamines during E. coli bacteremia in conscious rats
S B Jones1, M V Westfall, M M Sayeed
1Department of Physiology, Loyola University of Chicago, Stritch School of Medicine, Maywood, Illinois 60153.
The American Journal of Physiology
|March 1, 1988
Summary
Live Escherichia coli (E. coli) administration in rats causes significant sympathetic nervous system activation, leading to increased heart rate and lactate levels. Endotoxin tolerance attenuates this response, suggesting a mechanism for reduced septic shock symptoms.
Area of Science:
- Physiology
- Microbiology
- Immunology
Background:
- Sepsis, a life-threatening response to infection, involves complex host-pathogen interactions.
- The sympathetic nervous system plays a crucial role in the physiological response to bacterial infections.
Purpose of the Study:
- To investigate the impact of live Escherichia coli (E. coli) administration on the sympathetic nervous system in rats.
- To determine the effect of endotoxin tolerance on the physiological responses to live E. coli.
Main Methods:
- Male rats were administered live E. coli, with measurements of heart rate, blood pressure, and plasma levels of lactate, glucose, norepinephrine, and epinephrine.
- A separate group of rats received prior endotoxin tolerance induction.
- Physiological parameters and survival rates were compared between tolerant and non-tolerant groups.
Main Results:
- Live E. coli induced significant tachycardia and increased plasma norepinephrine and epinephrine levels in non-tolerant rats.
- Plasma lactate levels increased sixfold in rats treated with E. coli.
- Endotoxin-tolerant rats exhibited attenuated sympathetic activation (lower norepinephrine and epinephrine), reduced tachycardia, and no significant lactate increase, with improved survival.
Conclusions:
- Acute bacteremia with live E. coli triggers profound sympathetic nervous system activation.
- Endotoxin tolerance significantly reduces the sympathetic and metabolic responses to live E. coli, indicating a protective effect.
- Tolerance likely diminishes afferent stimuli during bacteremia, mitigating the severity of the host response.