Effect of theophylline on respiratory muscle function.
Theophylline improves diaphragmatic contractility of the respiratory muscles both in isolated muscle preparations, as well as in animals and normal human beings. Furthermore, theophylline restores diaphragmatic fatigue and prevents fatigue of the diaphragm when given prophylactically. Finally, it was recently shown that theophylline improves diaphragmatic function in COPD patients, all of whom were CO2 retainers (PaCO2 53 +/- 3 mm Hg) and hypoxemic (PaO2 57 +/- 8 mm Hg). Patients improved transdiaphragmatic pressure and were less susceptible to fatigue. Presently the mechanisms of action of theophylline regarding its effects on diaphragmatic function are not fully elucidated. Experimental evidence, however, suggests that theophylline may have an effect on transmembrane calcium movements by blocking adenosine receptors.
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D000628:Aminophylline / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000378:metabolism; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D003964:Diaphragm / Q000187:drug effects / Q000378:metabolism / Q000502:physiology / Q000503:physiopathology; D004285:Dogs; D006801:Humans; D066298:In Vitro Techniques; D007473:Ion Channels; D008173:Lung Diseases, Obstructive / Q000188:drug therapy / Q000503:physiopathology; D009119:Muscle Contraction / Q000187:drug effects; D009132:Muscles / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology; D051381:Rats; D012119:Respiration; D013806:Theophylline / Q000494:pharmacology*
D007473:Ion Channels; D000628:Aminophylline; D013806:Theophylline; D002118:Calcium