Browsing This

Influence of p2-Adrenergic Receptor Genotype on Airway Function During Exercise in Healthy Adults: Data Collection

Published in Pulmonary Function

Cardiopulmonary Assessment During Exercise: Measurements of oxygen uptake (Vo2) and the elimination of carbon dioxide were measured continuously during the various exercise tests and stages using a metabolic cart (Medical Graphics; St. Paul, MN) interfaced with a mass spectrometer (Perkin Elmer; Wellesley, MA). This system has been validated against classic “bag” collection techniques, and stability is verified by regular testing at standard exercise intensities by laboratory personnel.
Catecholamines (epinephrine and norepinephrine) were assessed according to methods developed in the Mayo Clinic GCRC immunochemical core laboratory and the methods of Sealey. For our laboratory, intraassay coefficient of variations (CVs) are as follows: norepinephrine, 4.5% and 3.3% at 224 pg/mL and 429 pg/mL; and epinephrine, 12.2% and 3.6% at 13.8 pg/mL and 242 pg/mL, respectively. Interassay CVs are as follows: norepinephrine, 8.2% and 6.3% at 337 pg/mL and 533 pg/mL; and epinephrine, 8.5% and 6.3% at 179 pg/mL and 390 pg/mL, respectively. www.buy-asthma-inhalers-online.com

At rest, during exercise, and then in the recovery period, subjects performed inspiratory capacity maneuvers followed by a MEFV maneuver. From the MEFV maneuver, maximal expiratory flow after 50% of the vital capacity (VC) [FEF50] has been expired was determined. To determine FEF50, MEFV curves were aligned at total lung capacity (maximal inflation volume) with the reference VC from the best pre-exercise maneuver, so that the data were analyzed at a consistent lung volume (isovolume FEF50). The FEF50 was chosen as the primary index of airway function, since this point along the maximal expiratory curve is in the effort-independent portion, does not require a sustained maximal effort for > 1 s, and because it is more responsive to change after an inhaled P-agonist than FEV1. FEF50 is also a point along the expiratory flow curve where subjects commonly breathe with heavy exercise. We have previously observed changes in the maximal expiratory flow rates over the mid-to-lower lung volumes combined with mild hyperinflation in patients with asthma during exercise, while no or minimal changes were observed in FEV1. In repeat measurements performed in our laboratory on 10 healthy subjects at rest and during exercise, the FEF50 was found to have CVs of 2.6% and 3.6%, respectively. The MEFV data were obtained on a separate mouthpiece and heated pneumotachograph (Hans Rudolph; Kansas City, MO) measurement system as previously described. Pre-exercise MEFV maneuvers were performed until two maneuvers were obtained that resulted in FVC and FEV1 values that differed by < 5%.