Influence of p2-Adrenergic Receptor Genotype on Airway Function During Exercise in Healthy Adults: Materials and Methods
These differences were not observed in children, suggesting the Arg16Gly polymorphism may influence the rate of decline in lung function with aging.
The focus of the present study was to determine if common polymorphisms of the (P2AR differentially influence airway tone during and after short-term exercise in healthy subjects without asthma. We hypothesized that subjects with homozygous Arg16 would have an attenuated bronchodilatory response at exercise intensities that induce catecholamine release (> 50% maximum workload),
The protocol was reviewed and approved by the Mayo Clinic Institutional Review Board, and all participants signed informed consent before entering the study. Age-, gender-, and activity-matched subjects were recruited from an existing pool of subjects who had previously been genotyped for the P2AR as a part of a large study of the genetic associations with BP. Forty-two individuals who were homozygous for arginine (Arg16, n = 16) or glycine (Gly16, n = 26) at codon 16, and had no exclusion criteria (cardiopulmonary abnormalities, pregnancy, inability to exercise) agreed to participate. All subjects were healthy nonsmokers, without asthma, and were not receiving any medications. http://birthcontroltab.com/
Before performing the exercise protocols, subjects underwent baseline pulmonary function testing, an incremental cycle ergom-etry test to exhaustion, a CBC count (CBC, to rule out anemia), and in women a pregnancy test. The pulmonary function testing included postbronchodilator measures (albuterol) to assess baseline differences between genotypes in airway response to a P-agonist, and were determined according to current American Thoracic Society recommendations. The baseline exercise study served as an initial familiarization session, was used to determine work intensities for subsequent sessions, and acted as a screening study to rule out ischemia and/or abnormal arrhythmias. Following these initial studies, subjects met with the General Clinical Research Center (GCRC) nutritionist and were put on a salt-neutral diet (3,450 mg/d) for 3 days with a 24-h urine collection to confirm sodium intake. A salt-neutral diet was used because previous studies have suggested that the P2AR may be sodium sensitive. Subjects subsequently returned to the GCRC on two occasions for exercise testing.