A reevaluation of the validity of unrestrained plethysmography in mice
Presently, unrestrained plethysmography is widely used to assess bronchial responsiveness in mice. An empirical quantity known as enhanced pause is derived from the plethysmographic box pressure [P-b( t), where t is time] and assumed to be an index of bronchoconstriction. We show that P-b(t) is determined largely by gas conditioning when normal mice breathe spontaneously inside a closed chamber in