The serotonin 5-hydroxytryptamine(1A/7) receptor agonist (R)-8-OH-DPAT (8-hydroxy-2-(di-n-propylamino)tetralin) (Sigma) and the 5-hydroxytryptamine(1A/1B/1D) agonist GR-46611 (3-[3-(2-dimethylaminoethyl)-1H-indol-5-yl]-N-(4-methoxybenzyl)acrylamide) (Tocris Cookson, Ellisville, Missouri) inhibit bladder activity during saline infusion into the bladder of cats with chronic spinal cord injury (saline infused, spinal cord injured cats), suggesting an effect on mechanosensitive bladder afferent C fibers or their targets. We investigated the effects of (R)-8-OH-DPAT and GR-46611 on bladder activity in chronic spinal cord injured cats during infusion of dilute acetic acid into the bladder to stimulate chemosensitive bladder afferent C fibers (acid infused, spinal cord injured cats).