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Pharmacogenetics of inhaled beta-2-agonists and athletic performance

University of British Columbia

The A46G single nucleotide polymorphism (SNP) and the C79G SNP of the adrenergic β2-receptor gene (ADRB2) are associated with the regulation of cardiorespiratory responses, to the inhalation of salbutamol, such as bronchodilation, heart rate and ventilation. PURPOSE: To determine (1) the effect of susceptibility to exercise-induced bronchoconstriction (EIB) and (2) the effect of genetic variation at the ADRB2 A46G and the C79G SNPs on athletic performance after the inhalation of salbutamol. METHODS: Genetic variation for the A46G SNP (AA: 4; AG: 15; GG: 21; unidentified: 2) and the C79G SNP (CC: 14; CG: 19; GG: 7; unidentified: 2) were genotyped in male cyclists with EIB (EIB+: 10) and without EIB (EIB-: 32), aged 19 – 40 years. Athletes performed two simulated 10-km time trials (TTs) on a cycle ergometer 60-min after the inhalation of either 400µg of salbutamol or placebo. FEV1 was assessed immediately before and 30-min after inhalation. Performance was measured by mean power output relative to body weight. Mixed between-within subject ANOVAs were conducted to assess differences in lung function and cycling performance, respectively, between the two treatments based on an individual’s susceptibility to EIB and based on genetic variation at the ADRB2 A46G and C79G SNPs. RESULTS: Change in FEV1 after the inhalation of salbutamol (M = 6.6%, SD = 6.3%) was greater compared to placebo (M = 1.1%, SD = 3.0%), p < 0.001. The improvement in FEV1 was greater in EIB+ athletes (M = 10.9 %; SD = 10.9%) compared to EIB- athletes (M = 5.3%; SD = 3.0%, p = 0.009). Performance was not altered regardless of the athletes’ susceptibility to EIB and genetic variation at the ADRB2 A46G and C79G SNPs. On average, athletes maintained 4.0W∙kg-¹ (SD = 0.3W∙kg-¹) after the inhalation of salbutamol and 4.0W∙kg-1 (SD = 0.4W∙kg-1) after the inhalation of a placebo. CONCLUSIONS: In male EIB+ and EIB- cyclists, FEV1 is improved after the inhalation of salbutamol (400µg). Despite this improvement in lung function, athletic performance during a 10-km TT was not altered regardless of susceptibility to EIB and genetic variation at the ADRB2 A46G and the C79G SNPs.

Text

2011-10-12

Attribution 3.0 Unported

http://hdl.handle.net/2429/37901

Kinesiology

University of British Columbia

UBCV

http://creativecommons.org/licenses/by/3.0/