Vanilloid receptors in the urinary bladder: regional distribution, localization on sensory nerves, and species-related differences.
Using selective surgical ablations we have investigated the localization of vanilloid receptors (specific [3H] resiniferatoxin binding sites) on terminals of the pelvic, hypogastric, and pudendal nerves in the rat urinary bladder. Pelvic and hypogastric nerve resections resulted in 90% and 25% loss of specific [3H] resiniferatoxin (RTX) binding sites, respectively, whilst pudendic nerve resection had no measurable effect on the binding. In control animals, the density of vanilloid receptors was 1.7-fold higher in the neck than in the dome of the urinary bladder; the Bmax values were 57 +/- 8 and 34 +/- 7 fmol/mg protein, respectively. The binding characteristics of the vanilloid receptor were similar in the urinary bladder of the rat and mouse: Kd values were 87 +/- 15 and 61 +/- 11 pM, Bmax values were 37 +/- 2 and 60 +/- 10 fmol/mg protein, respectively. In contrast to the findings for the rat and mouse, in the urinary bladder of the guinea pig and the hamster the low level of specific [3H]RTX binding prevented the detailed characterization of vanilloid receptors. Nonetheless, at a fixed (60pM) concentration of [3H]RTX, specific binding both in the guinea pig and hamster urinary bladder was approximately 20% of that in the rat urinary bladder. In the urinary bladder of newborn rats, as in adults, a single class of specific [3H]RTX binding sites was found which bound RTX with an affinity of 110 +/- 20 pM and with a maximal binding capacity of 30 +/- 5 fmol/mg protein.(ABSTRACT TRUNCATED AT 250 WORDS)
Szallasi
A
A
Pharmacology Department, Menarini Ricerche Sud, Pomezia, Roma, Italy.
Conte
B
B
Goso
C
C
Blumberg
P M
PM
Manzini
S
S
D000818:Animals; D000831:Animals, Newborn / Q000502:physiology; D002211:Capsaicin / Q000494:pharmacology; D006224:Cricetinae; D003714:Denervation; D004224:Diterpenes / Q000378:metabolism* / Q000493:pharmacokinetics; D006168:Guinea Pigs; D066298:In Vitro Techniques; D008647:Mesocricetus; D051379:Mice; D009475:Neurons, Afferent / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D011955:Receptors, Drug / Q000378:metabolism*; D013045:Species Specificity; D013373:Substance P / Q000276:immunology / Q000378:metabolism; D001743:Urinary Bladder / Q000033:anatomy & histology / Q000294:innervation / Q000378:metabolism*
D004224:Diterpenes; D011955:Receptors, Drug; D013373:Substance P; C024353:resiniferatoxin; D002211:Capsaicin