Study Of Circadian Rhythm Of Respiratory Function And LTE₄ In Nocturnal Asthma

Objective: 1 To clarify the circadian rhythm of lung function and respiratory drive in nocturnal asthma. 2 To investigate the circadian rhythm of inflammation mediator leukotriene E4 (LTE4). 3 To determine the relationship among urine LTE4 concentration, lung function and respiratory in nocturnal asthma.Methods: Three groups were studied : group A, ten nocturnal asthmatic patients; group B, eleven asthmatic patients without nocturnal attacks; group C, ten control subjects. Asthma was defined using the criteria of GINA 2002. Nocturnal asthma was defined as a documented fall in the overnight PEF ^15%, and nonnocturnal asthma was defined as a fall in the overnight PEF^10%. Lung function (PEF^ FEV1%> FEV1%FVC> MVV^ Vmax25, Vmax50) and respiratory drive (P0.t) were measured at 04:00, 08:00, 16:00, 22:00. Heart rate was monitored in 24 hours. Urine was collected over 24 hours in three samples (9:00 AM to 3:00 PM; 3:00PM to 9:00 PM; 9:00 PM to 9:00 AM). LTE4 was measured by EIA and expressed as picograms per milligram of creatinine.Results:(1) Both in nocturnal asthmatic group and control group, lung function was highest at 16:00 and lowest at 04:00. In nocturnal asthma the difference was significant (P<0. 05). In control group, the difference was not significant (P>0. 05). In non-nocturnal asthma lung function did not decrease at night. (2) Respiratory drive was significantly higher in asthmatic patients than in health. And respiratory drive did not take on circadian rhythm inall three groups. (3) A significant correlation was observed between the increase of P0.1 and the decrease of PEF, FEV1% at night in nocturnal asthma. (4) Urine LTE4 was significantly higher in asthmatic patients than in health. And in nocturnal asthma urine LTE4 at night was significantly higher than that of the other samples. (5) The change of LTE4 and lung function, respiratory did not take on significant relationship.Conclusions: (1) In nocturnal asthma, lung function took on circadian rhythm. (2) Respiratory drive was higher in asthma patients than in healthy samples. (3) In nocturnal asthma, the change of respiratory drive and lung function at night took on significant relationship. (4) LTE4 was a significant inflammation medium in asthma, and might contribute to the nocturnal worsening of asthma.