FUNCTIONAL-EFFECTS OF PHOSPHORAMIDON AND CAPTOPRIL ON EXOGENOUS NEUROPEPTIDES IN HUMAN NASAL-MUCOSA

The functional effects of the intranasal application of exogenous vaso active intestinal polypeptide (VIP), substance P (SP) and calcitonin g ene-related peptide (CGRP) were evaluated in 12 healthy volunteers bef ore and after neutral endopeptidase (NEP) inhibition with phosphoramid on (PA) and angiotensin-converting enzyme (ACE) inhibition with captop ril. The three neuropeptides increased nasal airway resistance (NAR) m easured by anterior rhinomanometry and superficial capillary blood flo w measured by laser Doppler flowmetry (LDF). After pretreatment of the nasal mucosa with PA, the effects of VIP, SP and CGRP on the LDF sign al, NAR and mucus production were potentiated, whereas local pretreatm ent with captopril did not modify these functional effects. These obse rvations suggest that NEP, but not ACE, may participate in the catabol ism of neuropeptides when applied directly to the human nasal mucosa. Furthermore, since these neuropeptides induced nasal obstruction, incr eased blood flow and rhinorrhea, a decreased activity of the enzymes i nvolved in their degradation could be involved in the physiopathology of rhinitis symptoms.