Neurokinin A-induced bronchial hyperresponsiveness to methacholine in Japanese monkeys.

The present study was designed to investigate whether neurokinin A (NKA) and substance P (SP) increase bronchial responsiveness to methacholine (MCh). Before and 1, 2, 3 and 4 weeks after three Japanese monkeys had inhaled 10(-8) M NKA and 10(-8) M SP for 2 min, bronchial responsiveness to inhaled MCh was evaluated. Pulmonary flow resistance (R1) and dynamic lung compliance (Cdyn) were used as pulmonary function tests. Dose-response curves of R1 to inhaled MCh were shifted to the left 1 to 4 weeks after NKA treatment, compared with that obtained before treatment. However, SP treatment did not change the R1 dose-response curve. Thus, bronchial responsiveness to MCh was increased by inhalation of 10(-8) M NKA in Japanese monkeys.