Role of neutral endopeptidase and kininase II on substance P-induced increase in nasal obstruction in patients with allergic rhinitis.

Abstract

We studied the role of neutral endopeptidase (NEP) and kininase II (angiotensin-converting enzyme; ACE) in the modulation of exogenous substance P (SP)-induced nasal response in normal subjects and in patients with allergic rhinitis. We measured the nasal conductance in response to increasing doses of SP 2 h after oral administration of either placebo or the ACE inhibitor, cilazapril (5 mg), or the NEP inhibitor, acetorphan (300 mg), given in a randomized, double-blind, cross-over manner. We performed three separate studies: acetorphan versus placebo and cilazapril versus placebo, in normal subjects (n = 6 and n = 8, respectively), and acetorphan versus cilazapril versus placebo in patients with allergic rhinitis (n = 6). In normal as well as in rhinitic subjects, SP decreased nasal conductance in a dose-dependent fashion (p < 0.001). With placebo, the decrease in nasal conductance in normal subjects was similar to that in patients with allergic rhinitis (p > 0.5). In normal subjects, acetorphan potentiated the decrease in nasal conductance (p < 0.001), whereas cilazapril did not (p = 0.12). In patients with allergic rhinitis, the decrease in nasal conductance was potentiated by acetorphan (p < 0.001) and by cilazapril (p < 0.001). With acetorphan, the decrease in nasal conductance was not different in patients with allergic rhinitis and in normal subjects (p > 0.9). Conversely, with cilazapril, the nasal response to SP was greater in patients with allergic rhinitis than in normal subjects (p < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)