Effects of high +Gz exposure on saliva sIgA and cortisol levels in pilots

Abstract

Objective To investigate the influence of positive (+Gz) acceleration exposure on saliva secretory immunoglobulin A (sIgA) and cortisol concentrations of pilots,so as to completely understand the characterisitics and mechanism of +Gz reaction.Methods Forty-seven high performance pilots trained on human centrifuge with the protection of G-suit.Their saliva was collected before and after + 6.5 Gz,+ 7.0 Gz,+ 8.0 Gz exposures on centrifuge.Saliva sIgA and cortisol concentrations were measured with chemiluminescent immunoassay immunoturbidimetry.Results ①Compared with the data got before exposures,saliva sIgA rose slightly after +6.5 Gz,+7.0 Gz,+ 8.0 Gz exposures.But there was no significant difference among them.Cortisol concentration in saliva collected after +6.5 Gz,+7.0 Gz,+8.0 Gz exposures was significantly higher than that before exposures (P＜0.05).Cortisol concentration after +8.0 Gz exposure was significantly higher than that after +6.5 Gz exposure,before +7.0 Gz exposure and before +8.0 Gz exposure (P＜0.05).②ANOVA analysis showed that aircraft types,age and total flying hours had no influence to saliva sIgA and cortisol concentrations during different exposures.③Pilot's salivary sIgA had no correlation with age,flying hours,aircraft types and the level of +Gz exposure.Salivary cortisol had negative correlation with pilot's age and aircraft types (r=-0.328,-0.694,P＜0.05),but had positive correlation with flying hours and the level of +Gz exposure (r=0.466,0.141,P＜0.05).Conclusions + Gz exposure has no effect on sIgA concentration.High acceleration exposure can lead to high cortisol concentration,but have no effect on mucosal immune functions.Saliva cortisol can be used as an indicator for monitoring high +Gz stress reaction. Key words: Acceleration; Saliva; Immunoglobulin A, secretory; Cortisol