Audétat V, Preisig R, Bircher J
Schweiz Med Wochenschr. 1977 Feb 19;107(7):231-5.
Microsomal demethylation, a partial function of the liver, can be estimated by the aminopyrine breath test. Both the determination of specific activity and the disappearance rate constant for 14CO2 in breath demand the assumption of rapid formaldehyde oxidation to CO2. Conversely, the disappearance of aminopyrine from plasma reflects microsomal aminopyrine metabolism only. Ethanol is known to affect both microsomal demethylation and formaldehyde metabolism. If in the presence of ethanol the latter process should become rate-limiting, a discrepancy between the data obtained in breath and in plasma could be expected. In order to investigate this possibility 10 fasting healthy male volunteers received 9 mg/kg (dimethylamine-14C)-aminopyrine (2 muCi) orally and, 3 hs later, 0.7 g/kg ethanol. Immediately following ethanol the specific activity of 14CO2 in breath decreased by 25% (p less than 0.005) and the disappearance of 14CO2 from breath was 31% lower than in 17 matched controls (p less than 0.005). The aminopyrine plasma disappearance rate, determined by GLC, decreased by 30% after ethanol (p less than 0.05). Since the decrease in aminopyrine plasma disappearance rate seems to account for the proportional decreases obtained by breath analysis, it is concluded that the aminopyrine breath test expresses the rate of microsomal demethylation even during altered formaldehyde metabolism, e.g. in acute ethanol intoxication.
微粒体去甲基化是肝脏的一项部分功能，可通过氨基比林呼吸试验进行评估。呼吸中14CO2的比活性测定和消失速率常数测定均需假设甲醛能快速氧化为CO2。相反，血浆中氨基比林的消失仅反映微粒体氨基比林代谢。已知乙醇会影响微粒体去甲基化和甲醛代谢。如果在乙醇存在的情况下，后一过程成为限速过程，那么呼吸和血浆中所获数据之间可能会出现差异。为了研究这种可能性，10名空腹健康男性志愿者口服9mg/kg（二甲胺-14C）-氨基比林（2μCi），3小时后再口服0.7g/kg乙醇。乙醇摄入后即刻，呼吸中14CO2的比活性下降了25%（p<0.005），呼吸中14CO2的消失比17名匹配对照者低31%（p<0.005）。通过气相色谱法测定，乙醇摄入后氨基比林血浆消失率下降了30%（p<0.05）。由于氨基比林血浆消失率的下降似乎可以解释呼吸分析中按比例下降的情况，因此得出结论，即使在甲醛代谢改变时，如急性乙醇中毒时，氨基比林呼吸试验也能反映微粒体去甲基化的速率。
