EFFECTS OF KAINIC ACID ADMINISTERED TO THE CAUDAL VENTROLATERAL MEDULLA ON ARTERIAL BLOOD-PRESSURE IN THE SPONTANEOUSLY HYPERTENSIVE AND NORMOTENSIVE WISTAR-KYOTO RATS

To compare the inhibitory influence of the caudal ventrolateral medull a (RVLM) on rostral ventrolateral medulla (RVLM) between spontaneously hypertensive (SH) and normotensive Wistar-Kyoto (WKY) rats, we studie d the blood pressure responses to administration of kainic acid, an ex citotoxic agent, to CVLM. Unilateral or bilateral administration of ka inic acid led to an initial reduction in blood pressure in both types of rats. In SH rats, this was followed by a gradual and sustained pres ser response. This biphasic response in arterial blood pressure was ob served in only one-third of the WKY rats. The elevation in blood press ure was significantly greater in SH than in WKY rats. The finding sugg ests that the tonic inhibitory influence from CVLM to RVLM may be grea ter in SH than in WKY rats.