Background:
The contribution of histamine (H
1) receptors inhibitory and/or β-adrenoceptors stimulatory mechanisms in the relaxant property of
Ferula assa-foetida
. (
F. asafoetida) was examined in the present study.
Methods:
We evaluated the effect of three concentrations of
F. asafoetida extract (2.5, 5, and 10 mg/mL), a muscarinic receptors antagonist, and saline on methacholine concentration-response curve in tracheal smooth muscles incubated with β-adrenergic and histamine (H
1) (group 1), and only β-adrenergic (group 2) receptors antagonists.
Results:
EC
50 values in the presence of atropine, extract (5 and 10 mg/mL) and maximum responses to methacholine due to the 10 mg/mL extract in both groups and 5 mg/mL extract in group 1 were higher than saline (P < 0.0001,
P = 0.0477, and
P = 0.0008 in group 1 and
P < 0.0001,
P = 0.0438, and
P = 0.0107 in group 2 for atropine, 5 and 10 mg/mL extract, respectively). Values of concentration ratio minus one (CR-1), in the presence of extracts were lower than atropine in both groups (P = 0.0339 for high extract concentration in group 1 and
P < 0.0001 for other extract concentrations in both groups).
Conclusion:
Histamine (H1) receptor blockade affects muscarinic receptors inhibitory property of
F. asafoetida in tracheal smooth muscle
