Effect of almitrine on upper airway muscle contraction in young and old rats

The effects of almitrine on the contractile properties of isolated geniohyo id and sternohyoid muscles were determined in physiological salt solution a t 30 degreesC in young and old rats. In young rats, almitrine had no effect on twitch or tetanic tension, twitch:tetanic tension ratio, contractile ki netics, active or passive tension-length relationships or frequency-tension relationship in both muscles. Almitrine significantly increased resistance to fatigue in both muscles. In old rats, almitrine had no effect on twitch or tetanic tension, twitch:tetanic tension ratio, contractile kinetics, ac tive or passive tension-length relationships, frequency-tension relationshi p or fatigue in both muscles. These results show that almitrine, in both yo ung and old rats, has no effect on most of the contractile properties of is olated geniohyoid and sternohyoid muscles. However, almitrine increases res istance to fatigue in both muscles in young but not in old rats. (C) 2001 E lsevier Science B.V. All rights reserved.