The effect of ambroxol on the vascular reactivity in the rabbit

Experiments were designed to determine whether ambroxol, a drug used for the treatment of respiratory disorders, affects the basal tension and/or contractions due to adrenergic stimuli in the isolated rabbit portal vein and pulmonary artery. Ambroxol in concentrations of 10(-6)-10(-4) mol/l produced a concentration-dependent increase in basal tension, but a decrease in spontaneous mechanical activity of portal vein. The same concentrations of ambroxol failed to influence basal tension of pulmonary artery. However, when the vessel tone was increased by exogenous noradrenaline, ambroxol elicited concentration-dependent contractions also in this vessel. Moreover, ambroxol in the concentration of 10(-5) mol/l significantly enhanced vascular contractions due to both exo- and endogenous noradrenaline. The results suggest that ambroxol, in biologically relevant concentrations, may influence or even induce vascular contractions to adrenergic stimuli. Their expression, however, depend on the type of vascular smooth muscle. (Fig. 7, Ref. 25.)