Airway smooth muscle force adaptation on the methacholine response in asthmatic patients

A sustained contraction of the airway smooth muscle (ASM) increases its contractility through force adaptation, but whether this alters the methacholine response in asthma is unknown. Asthmatic patients underwent two methacholine challenges with identical cumulative concentration but one including a period of ASM preactivation. The preactivation enhanced the response in patients with little inflammation but not in more inflamed patients. This suggests that force adaptation increases the methacholine response only in patients with low inflammation.