A quantification of heat load as assessed by indicators of tissue damage in rats.
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Date
1984
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Abstract
Heatstroke is an illness that occurs when body temperature is grossly
elevated, causing widespread tissue damage. The extent of tissue
damage depends on the level of body temperature elevation and the
duration. Despite the fact that the diagnosis of heatstroke is based
on sound scientific principles, namely the elevation of serum enzyme
levels as indicators of tissue damage, the sensitivity of these
parameters of tissue damage in the prodromal period of heatstroke is
less well established, especially for sub-lethal stress conditions.
Furthermore, it is not known to what extent given elevations in serum
enzyme levels reflect the nature of various combinations of hyperthermia
and its duration as sustained during the prodromal period.
In an attempt to throw some light on the questions posed above
anaesthetized rats were exposed to three different sets of thermal
conditions. However, the amount of heat gained over and above baseline
levels was controlled to a 20% rise irrespective of the experimental
conditions. Above this increment animals did not survive thus
indicating excessive stress. Plasma enzyme levels were assayed in
each group of animals upon termination of stress, six hours post-stress
and 24 hours post-stress in order to investigate the patterns of enzyme
release as well as the sensitivity of the respective indicators of
tissue damage.
On the basis of plasma enzyme assays, the tissue damage sustained
during these particular experimental conditions was mild to moderate,
completely reversible, not indicative of heatstroke but merely of
generalized tissue damage. The results suggest that in addition to
the established positive relationship between the level and duration
of hyperthermia and tissue damage, a third component,namely the rate
of rise in body temperature, nay constitute an important factor in
the ultirrate pathology. In this regard, i.e. sub-lethal stress,
creatine kinase proved to be the most sensitive and, therefore, the
most useful parameter of tissue damage.
Description
Thesis (M.Sc.)-University of Durban-Westville, 1984.
Keywords
Pathology, Experimental., Heatstroke., Theses--Physiology.