Actions of Two Main Metabolites of Propiverine (M-1 and M-2) on Voltage-Dependent L-Type Ca²⁺ Currents and Ca²⁺ Transients in Murine Urinary Bladder Myocytes

Abstract

The anticholinergic propiverine (1-methyl-4-piperidyl diphenylpropoxyacetate), which is used for the treatment of overactive bladder syndrome, has functionally active metabolites [M-1 (1-methyl-4-piperidyl diphenylpropoxyacetate N-oxide) and M-2 (1-methyl-4-piperidyl benzilate N-oxide)], but the site of actions of these metabolites is uncertain. Propiverine is rapidly absorbed after oral administration and is extensively biotransformed in the liver, giving rise to several active metabolites (M-1 and M-2). This study determines the effect of M-1 and M-2 on voltage-dependent nifedipine-sensitive inward Ca 2ϩ currents (I Ca ) using patch-clamp techniques and fluorescent Ca 2ϩ imaging [after electrical field stimulation (EFS) and acetylcholine (ACh)] in the murine urinary bladder. In conventional whole-cell recording, propiverine and M-1 but not M-2 inhibited the peak amplitude of I Ca in a concentration-dependent manner at a holding potential of Ϫ60 mV (propiverine, K i ϭ 10 M; M-1, K i ϭ 118 M). M-1 shifted the steady-state inactivation curve of I Ca to the left at Ϫ90 mV by 7 mV. Carbachol (CCh) reversibly inhibited I Ca . This inhibition probably occurred through muscarinic type 3 receptors, coupling with G-proteins, because nanomolar concentrations of 4-diphenylacetoxy-N-methyl-piperidine greatly reduced this inhibition, whereas pirenzepine or ,4]benzodiazepine-6-one (AF-DX 116) at concentrations up to 1 M was almost ineffective. In the presence of M-2, the CCh-induced inhibition of I Ca was blocked. In fluorescent Ca 2ϩ imaging, M-2 inhibited EFS-induced and ACh-induced Ca 2ϩ transients. These results suggest that M-1 acts, at least in part, as a Ca 2ϩ channel antagonist (as it inhibited I Ca ), whereas M-2 has more direct antimuscarinic actions.

Novel mechanism of hydrogen sulfide-induced guinea pig urinary bladder smooth muscle contraction: role of BK channels and cholinergic neurotransmission

“…In the urinary bladder, the activation of mAChRs by ACh depolarizes the DSM cell membrane potential, and so promotes the generation of Ca 2ϩ transients leading to overall enhancement of DSM contractility (17,18,54). Recently, it has been shown that in DSM cells type-3 mAChRs are functionally coupled to the BK channels, which mediate the mAChRinduced membrane depolarization (35,36).…”

Are Antimuscarinic Drugs Effective Against Urinary Frequency Mediated by Atropine-Resistant Contractions?

“…Propiverine is known to have an inhibitory effect on ACh-, KCl-, or CaCl 2 -induced contractile responses of human and rat detrusor muscles (2,21). Furthermore, propiverine has been demonstrated to inhibit Ca 2+ uptake in experiments conducted with isolated guinea-pig urinary bladder and murine urinary bladder myocytes and is known to be endowed with both antimuscarinic activity and Ca 2+ antagonistic activity (5,22).…”

Asiri Aktif Mesane Tedavisinde Karma Etkili Ajanların Etki Mekanizmasi ve Avantajlari

“…Karaciğerde sitokrom p450 sistemince elimine edildikten sonra M-1 (the propiverine N-oxide), ve M-2 (the N-oxide lacking the aliphatic side chain) isimli 2 metabolite dönüşür. Propiverinin oral alımını takiben mesanede en çok saptanan metabolitin M2 olduğu tespit edilmiştir (16,17). Voltaj bağımlı Ca +2 iyon kanallarının blokajı baz alınarak yapılan deneysel çalışmalarda M-1 metabolitinin L tipi voltaj bağımlı Ca +2 iyon kanallarına, M-2 metabolitinin ise daha çok muskarinik reseptörlere affinite gösterdiği gösterilmiştir.…”