[Regulative role of hypocapnia on cerebral blood flow under hypoxia in rats].
The experiments were performed on urethane anesthetized and artificially ventilated SD rats using a gascous mixture of 11.9% O2 and 88.1% N2. The PaCO2 was regulated by changing the volume of ventilation. The items to be studies are: (1) The correlation between hypocapnia and CBF under hypoxia; (2) the value of PaCO2 that can keep CBF at the level of hypoxic adapters; (3) the CBF change during a 5 h hypoxia-hypocapnia and (4) the reactivity of isolated basilar artery strips on hypoxia-hypocapnia. The results showed: (1) There was a significant correlation between the degree of hypocapnia and CBF under hypoxia. The correlation curve was steeper than that of normoxia. (2) When the ventilation was controlled at 25.5% above normoxic control value and the PaCO2 was about 2/3 of normoxic level under hypoxia, the CBF is near to the level of normoxic control. (3) When the PaCO2 was controlled at 2/3 of normoxic level, the CBF could still keep at the level of normoxic control for 5 h. (4) The tension of artery strip was decrease under hypoxia-normocapnia but increased under hypoxia-hypocapnia. Artery stripes with or without endotheliocyte make no difference in their tension changes due to changes of O2-CO2 tension.
Shanghai Institute of Physiology, Chinese Academy Sciences.
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D000818:Animals; D001488:Basilar Artery; D001784:Blood Gas Analysis; D002560:Cerebrovascular Circulation; D016857:Hypocapnia / Q000503:physiopathology*; D000860:Hypoxia / Q000503:physiopathology*; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction; D009131:Muscle, Smooth, Vascular; D011817:Rabbits; D051381:Rats; D017207:Rats, Sprague-Dawley