Fig. 4.  Intracolonic 8-methyl-N -vanillyl-trans -6-nonenamide (0.1 ml capsaicin, 0.1% [Cap]) instillation induces cross-organ sensitization in association with distribution of α-amino-3-hydroxy-5-methyl-4-isoxazoleproprionate receptors. (A , B ) Intracolonic instillation of vehicle solution (Veh) did not affect the reflex activity evoked by the test stimulation (TS). Although capsaicin induced no spontaneous background discharge in external urethra sphincter electromyogram activity, it dramatically increased the spike number evoked by the stimulation in a dose-dependent manner when drug concentration was increased up to 0.3%. **P < 0.01 compared with TS+Veh; ## P < 0.01 compared with TS+Veh. (C , D ) Immunoblotting showed that, when compared with preinstillation protein levels, capsaicin caused rapid increases in the expression of the Glu receptor 1 subunit (GluR1), PKA-A kinase–anchoring protein (AKAP), and the RII subunit of protein kinase A (PKA RII) in membrane fractions (P2) as associated with corresponding decreases in cytosolic fraction (S2) at 10–30 min postinstillation. EUSE = external urethra sphincter electromyogram; sec = seconds; uV =μvolts.