AIM: To test whether high-frequency electrical stimulation(HES) of the bilateral cervical vagus nerves reduces the airway responses to methacholine(MCh).METHODS: Guinea pigs were pretreated with saline(Sal, n = 9) or ovalbumin(Ova, n = 10) aerosol for two weeks(5 min/d, 5 d/wk) and subsequently anesthetized, paralyzed, tracheotomized and artificially ventilated. Both total lung resistance(RL) and dynamic pulmonary compliance(Cdyn) were recorded. In addition, the effects of vagal low-frequency electrical stimulation(LES, monophasic, 50 Hz) and HES(monophasic and biphasic, 1 and 2.5 kH z) for about 10 s or 2 min on the responses of RL and Cdyn to MCh aerosol-induced bronchoconstriction were compared in both groups of guinea pigs. In a few guinea pigs, the impact of bivagotomy on the RL responses to MCh was assessed.RESULTS: Before MCh challenge, LES, but not HES, significantly increased RL by about 30%(P < 0.01) and decreased Cdyn by about 20%(P < 0.01) similarly in both groups. MCh aerosol for 2 min elevated RL and diminished Cdyn more in Ova- than Sal-treated animals(RL: 313% ± 52% vs 113% ± 17%, P < 0.01; Cdyn:-56% ± 7% vs-21% ± 3%, P < 0.01). During MCh-induced airway constriction, LES further enhanced, but HES decreased RL and this decrease was greater in Ova-(about 45%) than Sal-treated animals(about 34%, P < 0.01) with little change in cardiovascular activity. On the other hand, LES further reduced whereas HES increased Cdyn more in Ova-(about 20%) than Sal-treated animals(about 13%, P < 0.01). In addition, bivagotomy almost eliminated the RL and Cdyn responses to MCh. CONCLUSION: We conclude that vagal HES is able to alleviate the bronchoconstriction induced by MCh in anesthetized guinea pigs, likely via reversible inhibition/blockade of vagal conduction. AIM: To test whether high-frequency electrical stimulation (HES) of cervical cervical vagus nerves reduces the airway responses to methacholine (MCh) .METHODS: Guinea pigs were pretreated with saline (Sal, n = 9) or ovalbumin (Ova, n = 10) aerosol for two weeks (5 min / d, 5 d / wk) and subsequent anesthetized, paralyzed, tracheotomized and artificially ventilated. Both total lung resistance (RL) and dynamic pulmonary compliance (Cdyn) were recorded. effects of vagal low-frequency electrical stimulation (LES, monophasic, 50 Hz) and HES (monophasic and biphasic, 1 and 2.5 kH z) for about 10 s or 2 min on the responses of RL and Cdyn to MCh aerosol-induced bronchoconstriction were In a few guinea pigs, the impact of bivagotomy on the RL responses to MCh was assessed .RESULTS: Before MCh challenge, LES, but not HES, significantly increased RL by about 30% (P <0.01 ) and decreased Cdyn by about 20% (P <0.01) similarly in both groups. MCh aero sol for 2 min elevated RL and diminished Cdyn more in Ova- than Sal-treated animals (RL: 313% ± 52% vs 113% ± 17%, P <0.01; Cdyn: -56% ± 7% vs. -21% ± 3%, P <0.01). During MCh-induced airway constriction, LES further enhanced, but HES decreased RL and this decrease was greater in Ova- (about 45%) than Sal-treated animals (about 34%, P <0.01) with little change in cardiovascular activity. On the other hand, LES further reduced compared HES increased Cdyn more in Ova- (about 20%) than Sal-treated animals (about 13%, P <0.01). In addition, bivagotomy almost eliminated the RL and Cdyn responses to MCh. CONCLUSION: We conclude that vagal HES is capable to alleviate the bronchoconstriction induced by MCh in anesthetized guinea pigs, likely via reversible inhibition / blockade of vagal conduction.