Am. J. Respir. Crit. Care Med., Vol 155, No. 2, 02 1997, 747-750.
Synergistic effect of nitric oxide and vasoactive intestinal peptide on bronchoprotection against histamine in anesthetized guinea pigs
H Kanazawa, T Kawaguchi, S Shoji, T Fujii, S Kudoh, K Hirata, N Kurihara and J Yoshikawa
The First Department of Internal Medicine, Osaka City University Medical School, Japan.
Vasoactive intestinal peptide (VIP) and nitric oxide (NO) are considered to
be nonadrenergic, noncholinergic (NANC) inhibitory neurostransmitters in
the airways. It seems likely that these neurotransmitters may be coreleased
and act as functional antagonists against bronchoconstrictor stimuli. In
the present study, we examined the synergistic effect of NO and VIP on
bronchoprotection against histamine in anesthetized guinea pigs. The NO
donor, S-nitroso-N- acetylpenicillamine (SNAP) significantly inhibited
histamine-induced bronchoconstriction in a dose-dependent manner. VIP also
inhibited histamine-induced bronchoconstriction in a dose-dependent manner,
but this bronchoprotective effect was short-lived. Additionally, VIP (10(-
9) M) had no significant bronchoprotective effect, but a subthreshold dose
of SNAP (10(-7) M) significantly potentiated VIP (10(-9) M)- induced
bronchoprotection against histamine. Moreover, SNAP (10(-7) M)
significantly enhanced VIP (10(-7) M)-induced bronchoprotection for a
longer period of time. On the other hand, VIP (10(-9) M) also significantly
potentiated SNAP-induced bronchoprotection against histamine. In
conclusion, combination therapy with NO donor and VIP receptor agonist may
have important advantages in the treatment of bronchial asthma, and both NO
and VIP may contribute in complementary fashion to the NANC-induced
relaxant response in guinea pig airways.