TY - JOUR T1 - Parasternal muscle contractility increases with aminophylline JF - European Respiratory Journal JO - Eur Respir J VL - 38 IS - Suppl 55 SP - p2123 AU - Jenny Jagers AU - Bruce Rothwell AU - Paul Easton Y1 - 2011/09/01 UR - http://erj.ersjournals.com/content/38/Suppl_55/p2123.abstract N2 - Introduction: The traditional theophylline bronchodilator, Aminophylline, is still widely used, especially in the treatment of COPD. However, in COPD patients the effects of theophylline have been inconsistent. Recently, Aminophylline was shown to increase ventilation and costal diaphragm contractility in awake canines (Jagers et al. Resp. Phys. 2009;167:273-280).Aim: To investigate the effect of Aminophylline at therapeutic levels on the primary chest wall muscle, Parasternal Intercostal.Methods: Sonomicrometry transducers and EMG electrodes were implanted in the left parasternal muscle. After recovery, the animals were studied awake, unanesthetized and breathing through a snout mask; air flow, ETCO2, heart rate, muscle length and shortening, and moving average EMG were recorded during room air, and CO2 stimulated ventilation, before and after loading and continuous infusion of Aminophylline at therapeutic levels.Results: For N=5 dogs (mean 31.1 kg) 24 days post implantation. Aminophylline serum levels were 66.4 umol/L (therapeutic range 55-110). Minute ventilation increased significantly with Aminophylline: 6.7, 7.84, 11.8 and 16.6 L/min at room air, low (46), medium (52) and high (57 mmHg) CO2 stimulated breathing respectively. Parasternal contractility increased significantly.Conclusion: Parasternal muscle contractility increases with greater muscle shortening per EMG, in awake, intact canines, at therapeutic levels of Aminophylline. ER -