Differences in transmission through the dorsal column nuclei in spontaneously hypertensive and Wistar Kyoto rats.

The medical lemniscal evoked potential in response to a range of footshock intensities was recorded in spontaneously hypertensive (SHR) and Wistar Kyoto rats (WKY). Input-output (I-O) relationships were constructed as the percent of maximum response at each intensity. The SHR had a steeper I-O relationship than did the WKY. This difference was also evident when SHR maintained normotensive from weaning with hydralazine were compared with identically treated WKY. The treatment itself steepened the I-O relationship of the SHR while leaving that of the WKY unchanged. These results indicate an inherent hyperresponsiveness in the SHR dorsal column nuclei and an inhibitory effect of elevated blood pressure on transmission through these nuclei.