Key words Temperature regulation
Gram-positive bacterial cell walls
Springer Online Journal Archives 1860-2000
Abstract Hypothalamic temperature (T hypo) and metabolic heat production (M) were measured in seven conscious rabbits injected intravenously with either saline or with Staphylococcus aureus, (8 · 107 cell walls · kg−1) while being subjected to a 3-h period of ramp-like total body cooling using a chronically implanted intravascular heat exchanger. In pyrogen-injected animals cooling started (1) at the time of injection or (2) 70 min after injection. In (1) the fall in T hypo induced by heat extraction was similar (1.0 °C) in afebrile and febrile animals. In (2) there was a transient increase in T hypo of about 0.5 °C at a time corresponding to the start of fever resulting in a significantly smaller fall in T hypo at the end of the 3-h cooling period (0.5 °C vs 0.9 °C, P 〈 0.05, n = 5). At this time in both (1) and (2) M was lower than theoretically expected from the increase in shivering threshold during fever. However, most of this effect can be explained when available data showing a decrease in thermosensitivity during S. aureus-induced fever are taken into account. After cessation of cooling in both groups of febrile animals T hypo rose to about 1 °C higher than the precooling level, which is comparable to the fever level in a separate series of experiments with S. aureus injection without cooling (1.2 °C).
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