Electrophysiological characteristics of sensory mechanisms in the kidney.

R2 chemoreceptors are excited by backflow of urine or isotonic KCl into the renal pelvis, they do not respond to backflow of isotonic saline at the same intrapelvic pressure but are excited during periods of renal ischemia. R1 chemoreceptors are excited during complete renal ischemia but otherwise exhibit no activity. The responses of multiunit afferent renal nerve activity (ARNA) to these stimuli in Sprague Dawley rats follow the same patterns exhibited by R2 chemoreceptors, and the data do not support the presence of mechanoreceptive nerves which are excited by increases in intrapelvic pressure in these animals. The responses of multiunit ARNA in SHR and WKY rats were not different from Sprague Dawley rats. In contrast, while the response of WKY rats during renal ischemia was not different from Sprague Dawley rats the excitation of SHR during ischemia was more than 10 fold greater than that of the normotensive animals.