Objective: To study the roles of N methyl D aspartate acid (NMDA) receptors of glutamate in mediating the arterial baroreceptor reflex (ABR)in rostral ventrolateral medulla (RVLM) in rats. Methods: The blood pressure, heart rates and ABR were observed after the bilateral microinjection of 0.1 ?l 50 mmol/L ketamine into RVLM of ureth anesthetized rats. Results: Bilateral microinjection of ketamine into RVLM induced decrease of the blood pressure and heart rate ( P