• Luis Prieto, Victoria López, Pablo Catalan, Desiree Barato, and Julio Marín.
• Sección de Alergologia, Asociacion Valenciana de Investigaciones Clinicas, Valencia, Spain prieto_jes@gva.es
• Ann. Allergy Asthma Immunol. 2009 May 1; 102 (5): 393-9.

BackgroundThe effect of adenosine monophosphate (AMP) on forced vital capacity (FVC) has never been systematically investigated.ObjectiveTo compare methacholine- and AMP-induced changes in FVC, as a marker of air trapping, in asthmatic patients treated and not treated with inhaled corticosteroids (ICSs).MethodsAirway responsiveness to equipotent concentrations of AMP and methacholine was obtained in asthmatic patients treated (n = 32) and not treated (n = 18) with ICSs. The response was expressed by the provocation concentration of agonist that caused a decrease in forced expiratory volume in 1 second (FEV1) of 20% (PC20) and by the slope of the FVC values recorded at each step of the challenge against the corresponding FEV1 values (sFVC).ResultsAlthough methacholine and AMP PC20 values were similar in patients treated and not treated with ICSs, the mean (95% confidence interval) methacholine sFVC (but not AMP sFVC) was higher in those treated with ICSs (0.91; 0.77-1.06) than in those not taking ICSs (0.69; 0.57-0.81; P = .03). No significant correlation was found between sFVC and PC20 values obtained with either methacholine or AMP. Methacholine and AMP sFVC values were significantly related, but only in the group treated with ICSs (r = 0.60, P < .001).ConclusionsAlthough the AMP-induced decline in FVC in asthmatic patients is similar to that observed with equipotent concentrations of methacholine, the apparently different effect of ICSs on changes in FVC induced by each agonist suggests that the information provided by the 2 bronchoconstrictor agents is not interchangeable and that the information generated by the analysis of the effect of each agonist on FEV1 and FVC may be complementary.

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