Developmental aspects of endothelin receptors in rabbit lower urinary tract

Since evidence of development/age‐related alterations of endothelin receptors in circulation and respiration systems has been increasing, we attempted to investigate the pharmacological characterization of endothelin receptors in neonatal, premature, and mature male rabbit lower urinary tract. The biochemical properties of ET receptors were examined in the lower urinary tracts of 1‐day (neonatal)‐, 6‐week (premature)‐, and 1‐year(mature)‐old male rabbits with binding technique utilizing [125I]ET‐1. The rank orders of the densities (Bmax values) of endothelin receptors in the bladder dome, bladder base, and urethra of different aged rabbits were bladder dome, 1 day > 6 week v̄Ls 1 year, bladder base, 1 day > 6 week v̄Ls 1 year, and urethra, 1 day > 6 week > 1 year. The pharmacological profiles of these binding sites inhibited by various kinds of endothelin receptor compounds showed similar Ki values and similar proportions of endothelin receptor subtypes in the same regions of 1‐day‐, 6‐week‐, and 1‐year‐old animals. Our data clearly demonstrated the presence of regional difference and development‐related changes in the density and subtype specificity of endothelin receptors in the lower urinary tract of the male rabbit. Neurourol. Urodynam. 19:71–85, 2000. © 2000 Wiley‐Liss, Inc.