Journal of Applied Physiology, Vol 54, Issue 1 234-243, Copyright © 1983 by American Physiological Society
Thermoregulation and acid-base status in the panting dehydrated fowl
Z. Arad
This is the first study to report on thermoregulation and acid-base
regulation in dehydrated and heat-exposed fowls. The dehydrated fowls (ca.
15% weight loss) panted at lower-than-normal panting frequencies, resulting
in a reduced evaporative water loss and a relative hyperthermy. However,
body temperature was effectively regulated below lethal levels, and heart
rate remained stable. Oxygen consumption was slightly increased compared
with normal hydration, when related to ambient temperature. However, when
related to body temperature, a lower metabolism was evident at the higher
range. Tidal and minute volumes were closely regulated, contributing to the
avoidance of extreme acid-base disturbances. Arterial pH level indicated a
relative metabolic acidosis compared with normal hydration. However,
acid-base regulation during heat exposure had not deteriorated despite the
lower arterial PCO2, due to a compensatory decrease in HCO-3 concentration.
The inhibited evaporative cooling and the relative hyperthermy suggest a
reduced responsiveness of the central regulatory system, possibly through
an elevated hypothalamic set point. In spite of these changes, regulation
of body temperature and acid-base status were not impaired.
