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DOI 10.1007/s10517-015-3055-x
712
Bulletin of Experimental Biology and Medicine, Vol. 159, No. 6, October, 2015 PHYSIOLOGY
Hypercapnia-Induced Changes in Cerebral Blood Flow against the Background of Experimental Cerebral Circulatory Failure
L. M. Kudaeva
Translated from Byulleten Eksperimentalnoi Biologii i Meditsiny, Vol. 159, No. 06, pp. 681-683, June, 2015 Original article submitted May 25, 2014
The peculiarities of hypercapnia-induced blood circulatory changes in the local cortical and subcortical regions of the brain and the character of disturbances of the adequate (vasodilator) responses to CO2 were examined on rabbits with experimental chronic cerebral circulatory failure. The study revealed moderation of local vasodilator effect of CO2 and reversal of the circulatory reactions to CO2 manifested in a decrease of local blood ow instead of its elevation. The data argue for individual use of carbogen therapy in relation to initial state of the functional organism systems.
Key Words: cerebral circulation; hypercapnia; cerebral circulatory failure; carbogen therapy
Carbogen therapy with a gas mixture consisting of O2 (97-93%) and CO2 (3-7%) is now successfully used for the treatment of various diseases accompanied by hypoxia. Effectiveness of such therapy is explained by the fact that CO2 pronouncedly affects the circula-tory and respiratory systems by centralizing the blood circulation resulting in elevation of blood supply to vitally important organs (brain and heart) and a decrease of blood inow to skeletal muscles [1,5,7]. The most signicant effect of carbogen therapy is observed in cerebral circulation: inhalation of a gas mixture with 3.5% CO2 up-regulates the blood supply to the brain by 10%, and 5-7% carbogen produces a 75% increment in this value [2,4,5]. Moreover, CO2 is a powerful spasm-relieving vasodilator for the blood vessels in brain and eyes [1,6].
The list of indications for carbogen therapy includes numerous diseases including coma, bronchial asthma, chronic bronchitis, respiratory center pareses, hypertension, vascular dystonia; it is also employed in prophylaxis and treatment of the postoperative
complications, cerebral circulatory failure, glaucoma, and ischemic optic neuropathies [1,6]. The carbogen therapy is characterized with multifactorial antihypoxic effect reecting the fact that inhaled carbogen shifts the oxy-Hb dissociation curve to the right, thereby prompting oxygen transfer to the tissues. It is of principal importance that CO2 is a far more effective stimulant for up-regulation of oxygen ow to the brain...