In vivo characterization of muscarinic receptors in peripheral tissues: evaluation of bladder selectivity of anticholinergic agents to treat overactive bladder.
The present study was undertaken to characterize in vivo muscarinic receptors in peripheral tissues (urinary bladder, submaxillary gland, colon, stomach, heart) of mice, and further to evaluate bladder-selectivity of anticholinergic agents to treat overactive bladder. Following i.v. injection of [3H]QNB in mice, the radioactivity in peripheral tissues was exclusively detected as the unchanged form. The in vivo specific [3H]QNB binding in particulate fraction of tissue homogenates of mice showed a pharmacological specificity which characterized muscarinic receptors. Binding parameters (Kd and Bmax) for in vivo specific [3H]QNB binding differed between mouse tissues. Oral administration of oxybutynin attenuated significantly in vivo specific [3H]QNB binding in all tissues of mice. From ratios of AUCurinary bladder/AUCother tissues of time-dependent muscarinic receptor occupancy, oral oxybutynin has been shown to exert little urinary bladder selectivity. Following oral administration of propiverine, there was a significant reduction of in vivo specific [3H]QNB binding in the urinary bladder, colon and submaxillary gland, but not in the stomach and heart. From the ratios of AUCurinary bladder to AUCsubmaxillary gland or AUCheart, it has been shown that oral propiverine exerts higher selectivity to muscarinic receptors in the urinary bladder than in the submaxillary gland and heart. Similarly, tolterodine displayed high selectivity to muscarinic receptors in the urinary bladder than in the submaxillary gland. Thus, the present study has demonstrated that [3H]QNB may be a useful ligand for in vivo characterization of muscarinic receptor binding of anticholinergic agents to treat overactive bladder. Propiverine and tolterodine have exhibited in vivo selectivity of muscarinic receptor in the mouse urinary bladder rather than in the submaxillary gland, and such receptor binding specificity may be the reason of lower incidence of dry mouth.
Maruyama
Shuji
S
Department of Pharmacokinetics and Pharmacodynamics and Global Center of Excellence (COE) Program, School of Pharmaceutical Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka, 422-8526, Japan.
Hasuike
Naoki
N
Suzuki
Kazuhiro
K
Yamada
Shizuo
S
D000284:Administration, Oral; D000818:Animals; D019540:Area Under Curve; D001559:Benzhydryl Compounds / Q000494:pharmacology / Q000627:therapeutic use; D001561:Benzilates / Q000494:pharmacology / Q000627:therapeutic use; D018680:Cholinergic Antagonists / Q000494:pharmacology* / Q000627:therapeutic use; D003408:Cresols / Q000494:pharmacology / Q000627:therapeutic use; D008297:Male; D008333:Mandelic Acids / Q000494:pharmacology / Q000627:therapeutic use; D051379:Mice; D018727:Muscarinic Antagonists / Q000494:pharmacology* / Q000627:therapeutic use; D010665:Phenylpropanolamine / Q000494:pharmacology / Q000627:therapeutic use; D011485:Protein Binding; D011813:Quinuclidinyl Benzilate / Q000031:analogs & derivatives / Q000378:metabolism; D011976:Receptors, Muscarinic / Q000187:drug effects* / Q000378:metabolism; D013997:Time Factors; D000068737:Tolterodine Tartrate; D053201:Urinary Bladder, Overactive / Q000188:drug therapy* / Q000503:physiopathology
C044493:1-benzilic-4,4'-quinuclidinyl benzilate; D001559:Benzhydryl Compounds; D001561:Benzilates; D018680:Cholinergic Antagonists; D003408:Cresols; D008333:Mandelic Acids; D018727:Muscarinic Antagonists; D011976:Receptors, Muscarinic; D010665:Phenylpropanolamine; C015586:propiverine; D000068737:Tolterodine Tartrate; D011813:Quinuclidinyl Benzilate; C005419:oxybutynin