Albuterol Improves Alveolar-Capillary Membrane Conductance in Healthy Humans.

BACKGROUND: Beta-2 adrenergic receptors (β2 ARs) are located throughout the body including airway and alveolar cells. The β2 ARs regulate lung fluid clearance through a variety of mechanisms including ion transport on alveolar cells and relaxation of the pulmonary lymphatics. We examined the effect of an inhaled β2 -agonist (albuterol) on alveolar-capillary membrane conductance (DM) and pulmonary capillary blood volume ( V C ) in healthy humans.

METHODS: We assessed the diffusing capacity of the lungs for carbon monoxide (DLCO) and nitric oxide (DLNO) at baseline, 30 minutes, and 60 minutes following nebulized albuterol (2.5 mg, diluted in 3 mL normal saline) in 45 healthy subjects. Seventeen subjects repeated these measures following nebulized normal saline (age = 27 ± 9 years, height = 165 ± 21 cm, weight = 68 ± 12 kg, BMI = 26 ± 9 kg/m2 ). Cardiac output (Q), heart rate, systemic vascular resistance (SVR), blood pressure, oxygen saturation, forced expiratory volume at one-second (FEV1 ), and forced expiratory flow at 50% of forced vital capacity (FEF50 ) were assessed at baseline, 30 minutes, and 60 minutes following the administration of albuterol or saline.

RESULTS: Albuterol resulted in a decrease in SVR, and an increase in Q, FEV1 , and FEF50 compared to saline controls. Albuterol also resulted in a decrease in V C at 60 minutes post albuterol. Both albuterol and normal saline resulted in no change in DLCO or DM when assessed alone, but a significant increase was observed in DM when accounting for changes in V C .

CONCLUSION: These data suggest that nebulized albuterol improves pulmonary function in healthy humans, while nebulization of both albuterol and saline results in an increase in DM/ V C .