CAN breathing oscillations reduce asthma medication?

Abstract

Airway hyperresponsiveness and obstruction are the major characteristics of asthma. Current asthma treatments using antiinflammatory agents and airway smooth muscle (ASM) relaxants are expensive, variable in effectiveness and are associated with several cardiovascular side effects. ASM behaviour in vitro has been studied by various researchers to possibly provide an explanation of its mechanical properties. Previous in vitro experiments conducted on ASM tissues suggest that length perturbations applied to contracted muscle result in a reduction in the contractile ability of the tissue. This study focuses on investigating the combined effects of bronchodilators and length oscillations on the dynamics of contracted ASM. Isolated porcine tracheal smooth muscle tissues are contracted using Acetylcholine. Isoproterenol (Iso), a ȕ-agonist, is used as a bronchodilator to relax the contracted ASM. Our results suggest that the combined effect of Iso and breathing oscillations is noted to be greater than the added effects of Iso and breathing alone. We speculate that, when breathing is combined with Iso, breathing facilitates the detachment of actomyosin bridges, while Iso prevents further phosphorylation of myosin heads, inhibiting the binding of myosin to actin.