[Hemodynamic effects of agmatine and its cellular mechanism in anesthetized rats]

The hemodynamic effects of intravenous injection of agmatine and their cellular mechanism were investigated in anesthetized rats. The results obtained are as follows. (1) Following intravenous injection of agmatine (10 mg/kg), HR, MAP, LVP, +/- LV dp/dtmax, CI and TPRI were significantly decreased. (2) Pretreatment with N-nitro-L-arginine (15 mg/kg) or methylene blue (50 mg/kg), did not affect the hypotensive effect of agmatine. (3) The hemodynamic effects induced by agmatine could be inhibited by prior intravenous injection of idazoxan (2 mg/kg), an alpha 2-adrenoceptor (alpha 2-AR) and imidazoline receptor antagonist. The results indicate that the hypotensive effect induced by i.v. agmatine may be attributed to the decrease in cardiac output resulting from depression of myocardial contractility, as well as to the reduction in total peripheral resistance resulting from vasodilatation. These effects of agmatine may be mediated by imidazoline receptor and/or alpha 2-AR.