麻酔中の赤血球炭酸脱水酵素（RCA）活性の変動—（第4報）換気状態の影響

Changes of Red Blood Cell Carbonic Anhydrase Activity during Anesthesia:IV Influence of Ventilation

　RCA　（Red Blood Cell Carbonic Anhydrase）は種々の疾患との関係で広い分野で検討されている_1〜3）。RCAは1分子に1個のZnを含む金属酵素であり，その作用は組織で産生されたCO₂を赤血球内に取り込んでH₂CO₃に変え，肺で逆の反応によりCO₂を排泄することである。

　そのためRCA活性が低下するとCO₂排泄に障害を来たし，組織にCO₂が貯留する結果となる^4,5）。このことから逆にCO₂の増減に対しRCA活性がどのように変化するか興味がもたれる点であり，肺胞でCO₂を早く排泄するために理論的にRCA量や活性値は増加しなければならないと予測される。

CO₂ retention in tissue follows the interrup-tion of CO₂ excretion when the RCA activity is decreased. It is very interested that the RCA activity changes when CO₂ in blood increases and decreases. It is supposed that the RCA acti-vity must be increased in order to fastly excrete CO₂ at alveolas.

It was reported that the RCA activity increas-es in the diseases with high Pa_CO2 as cyanide CHD, smoker, cyanide intoxication and COLD, but there was also report that RCA activity dose not change in these diseases. The special correla-tion between the RCA activity and Paco, has not been established. Then, RCA activity and the blood gas were measured by the Wilbur & Anderson's method and ABL-1^® of Radiometer Co. with the passage of time (pre-induction, 30 min., 60 min., 120 min., 180 min. of anesthesia and st day after operation) in 27 patients during fluothane-N₂0 anesthesia in which the blood gas can be easily changed as we tried to find out the relation between the RCA activity and Paco₂ and the relationships between Paco₂ acid-base balance and the RCA activity were compared among three groups which had been separated retrospectively to hypocapnia, normocapnia and hypercapnia groups.