Effect of chronic non-immunologically mediated bronchoconstriction on bronchial smooth muscle in the guinea pig

Immature guinea pigs underwent eight weeks of methacholine-induced wheezing on a daily basis. At the end of the study the treated guinea pigs showed less of a weight gain than control animals. Relative dry tracheal weight was greater in the methacholine group than in controls. However, there were no differences noted on histologic examination of the lungs between the treated and control animals. Although experimentally induced amounts of bronchoconstriction may not be extrapolated to the same degree as seen in asthma, these findings suggest that repeated bronchoconstriction alone is not the cause of the smooth muscle hypertrophy and hyperplasia found in asthma.