Objective: To study the role of endothelin 1 (ET 1), a potent vasoconstrictor originally isolated from vascular endothelial cells, within the nucleus tractus solitarius (NTS) in central cardiovascular control. Methods: To observe the changes in blood pressure, heart rate, left ventricular systolic pressure and ±dp/dt max , and arterial baroreflex sensitivity after a unilateral microinjection of ET 1 into the NTS of anesthetized rats, and observe whether these changes could be inhibited by preinjection of ET antagonists into the NTS or by intravenous pretreatment with a ganglionic blocker. Results: In urethane anesthetized rats, a unilateral microinjection of ET 1 (1.0, 3.3, 10.0 pmol) into the NTS significantly increased arterial pressure, left ventricular systolic pressure and ±dp/dt max in a dose dependent manner,and slightly decreased heart rate in a non dose dependent manner. The pressor response lasted more than 90 min. Neither PD147953, a selective ET A receptor antagonist, nor PD142893, a mixed ET A and ET B receptor antagonist, micro injected into the NTS elicited any changes in arterial pressure or heart rate. The pressor and bradycardiac effects evoked by a microinjection of ET 1 into the NTS could be blocked by local pretreatment with PD142893, and completely eliminated by intravenous pretreatment with ganglionic blocker hexamethonium. The arterial baroreflex sensitivity was almost totally suppressed by a microinjection of ET 1 (3.3 pmol) in α chloralose anesthetized rats. Conclusion: ET 1 modulates reflex control of hemodynamics by activation of autonomic nerve via ET A receptors in the NTS.