Muscarinic Cholinergic Receptor Subtypes in Human Detrusor Muscle Studied by Labeled and Nonlabeled Pirenzepine, AFDX-116 and 4DAMP
- 1 January 1995
- journal article
- research article
- Published by S. Karger AG in Urologia Internationalis
- Vol. 54 (3) , 150-153
- https://doi.org/10.1159/000282710
Abstract
The densities of M1, M2 and M3 muscarinic receptors in human detrusor muscle were measured using 3H-pirenzepine (3H-PZP), 3H-AFDX-116 (3H-AFDX) and 3H-4-diphenyl-acetoxy-N-methyl-piperidine methidide (3H-4DAMP). The affinities of PZP, AFDX and 4DAMP for human detrusor were determined in inhibition experiments with ¾-quinuclidinyl benzilate (3H-QNB). Saturation experiments with 3H-PZP, 3H-AFDX and 3H-4DAMP revealed the presence of M1, M2 and M3 receptors in human detrusor. The KD values (nM) and the Bmax values (fmol/mg protein) (mean ± SD, n = 6) were 0.84 ± 0.15 and 13.04 ± 1.54 for 3H-PZP, 0.68 ± 0.21 and 9.30 ± 1.10 for 3H-AFDX, and 0.25 ± 0.13 and 102.1 ± 7.40 for 3H-4DAMP. These data indicate that the bladder muscarinic receptors consist mainly of the M3 subtype. Nonlabeled PZP, AFDX and 4DAMP inhibited the 3H-QNB binding to human detrusor with Ki values (nM) (mean ± SD, n = 6) of 243 ± 62.5, 59.7 ± 15.3, 2.69 ± 0.96, respectively. Human detrusor was found to have a high affinity for 4DAMP. These data suggest that M3 muscarinic receptors are biochemically predominant in human detrusor muscle.Keywords
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