TY - JOUR T1 - ACTIVATION OF PREJUNCTIONAL P2X2/3 HETEROTRIMERS BY ATP ENHANCES THE CHOLINERGIC TONE IN OBSTRUCTED HUMAN URINARY BLADDERS JF - Journal of Pharmacology and Experimental Therapeutics JO - J Pharmacol Exp Ther DO - 10.1124/jpet.119.261610 SP - jpet.119.261610 AU - Miguel Silva-Ramos AU - Isabel Silva AU - Miguel Faria AU - Fatima Ferreirinha AU - Paulo Correia-de-Sa Y1 - 2019/01/01 UR - http://jpet.aspetjournals.org/content/early/2019/10/21/jpet.119.261610.abstract N2 - Objective: To investigate the role of ATP on cholinergic neurotransmission in the urinary bladder of control men and obstructed patients due to benign prostatic hyperplasia (BPH). Patients and methods: Human detrusor samples were collected from 41 patients submitted to transvesical prostatectomy due to BPH and 26 male organ donors. The release of [3H]acetylcholine ([3H]ACh) was evoked by electrical field stimulation (10 Hz, 200 pulses) in urothelium-denuded detrusor strips. Myographic recordings were performed to test detrusor strips sensitivity to ACh and ATP. Results: Nerve-evoked [3H]ACh release was 1.5-fold higher in detrusor strips from BPH patients compared to controls. This difference was abolished after desensitization of ionotropic P2X1-3 receptors with the ATP analogue, alpha,beta-MeATP (30 µM, applied for 15 min). TNP-ATP (10 nM, a preferential P2X2/3 antagonist) and A317491 (100 nM, a selective P2X3 antagonist) were about equipotent in decreasing nerve-evoked [3H]ACh release in control detrusor strips, but the selective P2X1 receptor antagonist, NF023 (3 µM), was devoid of effect. The inhibitory effect of TNP-ATP (10 nM) increased from 27±9% to 43±6% in detrusor strips of BPH patients, but the effect of A317491 (100 nM) was kept unaltered (20±2% vs. 24±4%). The amplitude of ACh (0.1-100 µM)-induced myographic recordings decreased, whereas sensitivity to ATP (0.01-3 mM) increased, in detrusor strips from BPH patients. Conclusions: Besides the well-characterized P2X1 receptor-mediated contractile activity of ATP in pathological human bladders, we show here for the first time that cholinergic hyperactivity in the detrusor of BPH patients is facilitated by activation of ATP-sensitive P2X2/3 heterotrimers.SIGNIFICANCE STATEMENT Bladder outlet obstruction often leads to detrusor overactivity and reduced bladder compliance in parallel to atropine-resistant increased purinergic tone. Our data show that P2X1 purinoceptors are overexpressed in the detrusor of patients with benign prostatic hyperplasia. Besides the P2X1 receptor-mediated detrusor contractions, ATP favors nerve-evoked acetylcholine release via the activation of prejunctional P2X2/3 excitatory receptors in these patients Thus, our hypothesis is that manipulation of the purinergic tone may be therapeutically useful to counteract cholinergic overstimulation in obstructed patients. ER -