Spinoreticular cell responses to renal venous and ureteral occlusion.

Responses of 65 thoracolumbar spinoreticular neurons to renal vein or ureteral occlusion were studied in 40 alpha-chloralose-anesthetized cats. Cells were antidromically activated from the medial medullary reticular formation and all responded to somatic stimuli as well as renal nerve stimulation. Renal vein occlusion excited 17 of 40 cells. Activity increased from 6 +/- 1 to 13 +/- 2 spikes/s, with little adaptation. Depressor responses occurred in 9 cats and pressor responses in 12 cats. Pressor responses, but not depressor responses, were abolished by renal denervation. Ureteral occlusion increased activity of 28 of 50 cells. Responses were always rapid in onset but were either nonadapting, slowly adapting, or completely adapting. Activity increased from 7 +/- 1 to a peak of 17 +/- 3 spikes/s. Pressor responses occurred in 22 of 25 cats and tachycardia in 15 cats. Transection of renal nerves abolished cardiovascular responses. Twenty-five cells were tested for responses for both stimuli. Ten were excited by both, six by only ureteral occlusion, and nine failed to respond to either. The responding group of cells had a significantly greater incidence of A delta- and C-fiber renal input compared with nonresponding cells. Nonresponding cells tended to have only A delta-input. The results show that renal and ureteral mechanical stimuli which evoke cardiovascular reflexes excite spinoreticular cells. These cells may be part of supraspinal reflex arcs initiated by renal receptors.