Intrathecal kynurenate reduces arterial pressure, heart rate and baroreceptor-heart rate reflex in conscious rats

Abstract

In the present study, an excitatory amino acid (EAA) pathway in the spinal cord which maintains sympathetic vasomotor tone in conscious rats has been investigated. To this end, the cardiovascular effects of an intrathecally administered EAA antagonist, kynurenate (KYN), were studied in conscious rats. KYN (0.5 μmol in 10 μl) caused a dramatic reduction in mean arterial pressure (MAP) and heart rate (HR) that persisted for 2-3h, and also resulted in extensor paralysis of the hindlimbs. The time courses of fall in MAP and HR and hindlimb paralysis were similar. Baroreceptor-HR reflex activity was also markedly impaired after KYN, suggesting functional diminution of sympathetic outflow at the l..