[Mechanism of ethanol-induced bronchoconstriction in Japanese asthmatic patients]

Acute ingestion of alcoholic beverages causes no changes in the expiratory airflow rates of most Occidental asthmatic patients. However, asthmatic symptoms are worsened after drinking small amounts of alcohol in Japanese asthmatic patients. Our laboratory results showed that the ingestion of pure ethanol caused a fall in FEV1.0 in about half of the Japanese asthmatic patients tested. The mechanism of ethanol-induced bronchoconstriction remains unclear. In order to investigate this mechanism, we performed oral-provocation tests with 10% ethanol in vivo, and leukocyte histamine release assay induced by ethanol and acetaldehyde in vitro. 55% of asthmatics showed a significant fall in FEV1.0 after ingestion of 10% ethanol (responder). There was no difference in the rise of blood ethanol concentration between the responder group and non-responder group. Acetaldehyde and histamine concentration in the responder group were significantly higher than in the non-responder group. Leukocyte histamine release assay showed that acetaldehyde (2 microM-100 microM) caused dose-dependent histamine release, whereas, ethanol (2 mM-100 mM) had no effect on histamine release. Our data indicate that histamine release from mast cells (or basophils) caused by acetaldehyde may play an important role in ethanol-induced bronchoconstriction. This is the first report on the mechanism of ethanol-induced bronchoconstriction in Japanese asthmatic patients.