Agmatine inhibits carotid sinus baroreflex in anesthetized rats
Abstract
Aim: To study the effect of agmatine (Agm) on carotid sinus baroreflex.
Methods: The functional parameters of baroreflex were measured by perfusing the carotid sinus in anesthetized rats.
Results: (1) Agm 1, 5, and 10 mmol/L shifted the functional curve of carotid sinus baroreflex to the right and upwards in a concentration-dependent manner with a reduction in peak slope and a reflex decrease in mean arterial pressure, indicating that Agm exerted an inhibitory effect on the carotid baroreflex. (2) The inhibitory effect of Agm (5 mmol/L) on baroreflex was eliminated by pretreatment with idazoxan (Ida, 0.1 mmol/L), an alpha2-adrenoceptor (alpha2-AR) and imidazoline receptor (IR) antagonist, and partially blocked by yohimbine (Yoh, 15 micromol/L), a selective alpha2-AR antagonist. (3) NG-nitro-L-arginine methyl ester (L-NAME, 500 micromol/L), an NOS inhibitor, did not affect the inhibitory effect of Agm.
Conclusion: Agm inhibits carotid baroreflex via IR and alpha2-AR.
Keywords:
Methods: The functional parameters of baroreflex were measured by perfusing the carotid sinus in anesthetized rats.
Results: (1) Agm 1, 5, and 10 mmol/L shifted the functional curve of carotid sinus baroreflex to the right and upwards in a concentration-dependent manner with a reduction in peak slope and a reflex decrease in mean arterial pressure, indicating that Agm exerted an inhibitory effect on the carotid baroreflex. (2) The inhibitory effect of Agm (5 mmol/L) on baroreflex was eliminated by pretreatment with idazoxan (Ida, 0.1 mmol/L), an alpha2-adrenoceptor (alpha2-AR) and imidazoline receptor (IR) antagonist, and partially blocked by yohimbine (Yoh, 15 micromol/L), a selective alpha2-AR antagonist. (3) NG-nitro-L-arginine methyl ester (L-NAME, 500 micromol/L), an NOS inhibitor, did not affect the inhibitory effect of Agm.
Conclusion: Agm inhibits carotid baroreflex via IR and alpha2-AR.