Modulation of capsaicin induced airway reflexes in humans: effect of monoamine oxidase inhibition.
1. In animal studies monoamine oxidase (MAO) inhibition has been shown to reduce the cough response through elevation of 5-HT in the central nervous system. In this study the effect of selective inhibition of the two subtypes of MAO (MAO-A and MAO-B) was studied on human airway reflexes. 2. Capsaicin-induced cough and reflex increase in respiratory resistance were measured in nine normal volunteers before and after MDL 72394 (MAO-A inhibitor) 16 mg or MDL 72974A (MAO-B inhibitor) 12 mg. 3. Neither inhibitor altered capsaicin-induced cough. Following treatment with MDL 72394, however, the capsaicin-induced reflex increase in resistance was enhanced, by 5.97 +/- 2.1 fold of the placebo value at 1 h. 4. Thus, neurotransmitters in the central nervous system which are substrate for MAO-A (i.e. noradrenaline, 5-HT) may be involved in the control of capsaicin-induced reflex bronchoconstriction.
Choudry
N B
NB
Department of Clinical Pharmacology, Royal Postgraduate Medical School, London.
Studham
J
J
Harland
D
D
Fuller
R W
RW
D000328:Adult; D000403:Airway Resistance / Q000187:drug effects*; D000498:Allyl Compounds; D000704:Analysis of Variance; D016084:Bronchoconstriction / Q000187:drug effects*; D002082:Butylamines / Q000494:pharmacology; D002211:Capsaicin / Q000494:pharmacology*; D003371:Cough / Q000139:chemically induced; D006801:Humans; D008297:Male; D008996:Monoamine Oxidase Inhibitors / Q000008:administration & dosage / Q000494:pharmacology*; D014443:Tyrosine / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000494:pharmacology
D000498:Allyl Compounds; D002082:Butylamines; D008996:Monoamine Oxidase Inhibitors; C058000:mofegiline; D014443:Tyrosine; C046880:beta-fluoromethylene-3-tyrosine; D002211:Capsaicin