Fig. 1.
Effects of protons and capsaicin on bladder sensory neurons from saline (control)- and cyclophosphamide (CYP)-treated rats. Protons triggered predominantly a multiphasic current (A and C), whereas capsaicin always produced a sustained current in the same lumbosacral (LS) and thoracolumbar (TL) bladder neurons from saline-treated rats. The same current profiles were evident in LS and TL neurons from CYP-treated rats (B and D), although proton-evoked current was reduced and capsaicin-evoked current was increased in both LS and TL neurons from CYP-treated rats. Proton-evoked effects were concentration dependent. Concentration-response relationships for fast (E and I), intermediate (F and J), and sustained (G and K) current components are plotted as current density (I) against pH in LS and TL bladder neurons. Open and filled circles represent values from saline (Sal)- and CYP-treated rats, respectively. EC50 values were not different after CYP treatment, but maximal current (Imax) in response to acid was substantially reduced for all current components in both LS and TL neurons. In contrast, capsaicin (1 μM) triggered significantly greater current density in LS (H) and TL (L) bladder neurons from CYP-treated rats. *P < 0.05.