[Changes in cerebral extracellular pH, cerebral blood flow and intracranial pressure induced by hypercarbic ventilation--assessment as a potential in vivo model of XXXX ].

@entity428 @entity75 @entity63 @entity515 @entity520 @entity35
The effects of @entity520 on @entity63 @entity75 are unclear and probably diverse. To establish an in vivo model of @entity520 , the authors assess changes in extracellular brain pH (pHe), CBF and @entity428 induced by hypercarbic ventilation, and discuss the reliability and short comings of this experimental model. @entity520 was induced by increasing the inspired @entity515 concentration in mechanically ventilated @entity35 . pHe was measured with a pH-sensitive electrode implanted into the cortical mantle. The @entity35 were divided into five groups according to the @entity515 concentrations inspired: G-1, 0% control; G-2, -5-% @entity515 ; G-3, -10-% @entity515 ; G-4, -20-% @entity515 ; G-5, -25-% @entity515 . Cortical blood flow was measured using a laser Doppler flowmeter, and @entity428 was also determined in each of the experimental groups. pHe decreased rapidly after the @entity515 supply was turned on and remained almost constant at fixed concentrations of inspired @entity515 . pHe values diminished as the concentration of inspired @entity515 decreased, as follows: G-2, -0.10 +/- 0.03; G-3, -0.31 +/- 0.08; G-4, -0.49 +/- 0.09; G-5, -0.64 +/- 0.10. The changes in pHe almost perfectly paralleled the changes in blood pH. The percentage increase in CBF was more than 200% in the G-2 groups and minimal increases in CBF, probably due to changes in blood pressure, were observed in from G-2 to G-5. Changes in CBF paralleled changes in systemic blood pressure, especially after the @entity515 supply was turned off. @entity428 also rose after increasing the @entity515 supply, and the pattern of changes was similar to that of CBF.(ABSTRACT TRUNCATED AT 250 WORDS)
