Circadian Characteristics of Urinary Leukotriene E4 in Healthy Subjects and Nocturnal Asthmatic Patients

摘要

Study objectives: Circadian rhythmicity of cysteinyl leukotrienes (LTs) and thromboxane (TX)-A2 in healthy subjects and nocturnal asthmatic patients remains a subject of controversy. The aim of this study was to investigate the contribution of these mediators to the pathogenesis of nocturnal asthma.nnMethods: We measured peak expiratory flow rate, urinary concentration of LTE4, 11-dehydro-TXB2, and creatinine eight times every 3 h in three groups: healthy control subjects (n = 5, group A), nocturnal asthmatic patients (n = 9, group B), and nonnocturnal asthmatic subjects (n = 9, group C). To evaluate the reproducibility of the measurement of urinary LTE4, we measured urinary LTE4 in group A for 3 separate days.nnResults: The urinary LTE4 concentrations from 3 to 6 AM were significantly (p < 0.05) higher than from 3 to 6 PM in both group A and group B, but not in group C. The mean levels of LTE4 in group B and group C were significantly higher (p < 0.05) than those in group A. In group B, another small peak was observed from 6 to 9 PM. No significant day-to-day variation was observed in group A. Urinary 11-dehydro-TXB2 values from 3 to 6 AM were significantly (p < 0.001) higher than those levels from 3 to 6 PM in all groups, and the mean levels in group B and group C were significantly higher than those in group A (p < 0.05).nnConclusions: Circadian rhythmicity of urinary LTE4 with a morning peak was found in healthy control subjects and nocturnal asthmatic subjects, but not in nonnocturnal asthmatic patients. It was suggested that cysteinyl LTs rather than TXA2 might contribute to the nocturnal worsening of asthma.