M. Maskrey et Cfl. Hinrichsen, RESPIRATORY RESPONSES TO COMBINED HYPOXIA AND HYPOTHERMIA IN RATS AFTER POSTERIOR HYPOTHALAMIC-LESIONS, Pflugers Archiv, 426(5), 1994, pp. 371-377
Urethane-anaesthetised rats were exposed to hypoxia (7% O-2 in N-2) fo
r 5 min periods while body core temperature (T-bc) was maintained with
in the normal range (37-38 degrees C) using an abdominal heat exchange
r. Animals were exposed to hypoxia and after placement of electrolytic
lesions in either the anterior (n = 6) or posterior hypothalamus (It
= 6). Neither lesion altered respiration while rats breathed air at ei
ther T-bc. At normal T-bc, rats responded to hypoxia with increased ve
ntilation throughout the exposure period. This response was unchanged
by lesions in either location. At reduced T-bc rats responded to hypox
ia with an initial increase in ventilation followed by depression to b
elow air-breathing levels. This depressive response was unchanged afte
r anterior hypothalamic lesions but eliminated after posterior hypotha
lamic lesions. It is concluded that neurons either originating in the
posterior hypothalamus, or passing through it, play a role in the inte
raction between cold and hypoxia which leads to inhibition of respirat
ion.