Agmatine inhibits carotid sinus baroreflex in anesthetized rats

AIM: To study the effect of agmatine (Agm) on carotid sinus baroreflex. MET HODS: The functional parameters of baroreflex were measured by perfusing th e 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 u pwards in a concentration-dependent manner with a reduction in peak slope a nd 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 idazoxa n (Ida, 0.1 mmol/L), an alpha (2)-adrenoceptor (alpha (2)-AR) and imidazoli ne receptor (IR) antagonist, and partially blocked by yohimbine (Yoh, 15 mu mol/L), a selective alpha (2)-AR antagonist. (3) N-G-nitro-L-arginine meth yl ester (L-NAME, 500 mu mol/L), an NOS inhibitor, did not affect the inhib itory effect of Agm. CONCLUSION: Agm inhibits carotid baroreflex via IR and alpha (2)-AR.