Article date: June 2004
By: Brian F King, Ian D Knowles, Geoffrey Burnstock, Andrew G Ramage in Volume 142, Issue 3, pages 519-530
The effects of purinoceptor ligands for P2X1 and/or P2X3 receptors (α,β‐meATP, IP5I, TNP‐ATP, MRS 2179, PPADS, Phenol red and RO116‐6446/008; i.v., n=4–5) and for P2Y1 receptors (PPADS, MRS 2179 and MRS 2269; i.v., n=3–5) were investigated on the distension‐evoked ‘micturition reflex’ in the urethane‐anaesthetized female rat.
α,β‐meATP (180 nmol kg−1 min−1), IP5I (10, 30 and 100 nmol kg−1), TNP‐ATP (1 μmol kg−1), MRS 2179 (1 μmol kg−1) and PPADS (17 μmol kg−1) each caused maintained bladder contractions to occur during the infusion of saline into the bladder. PPADS (17 μmol kg−1 min−1) had a similar effect when infused intravesicularly. Regular bladder contractions were not observed until the infusion of saline was halted. For IP5I, TNP‐ATP, MRS 2179 and PPADS, the magnitude of postinfusion isovolumetric contractions was significantly reduced and, for IP5I, this action was also associated with a significant reduction in urethral relaxation. Additionally, TNP‐ATP caused a significant increase in the pressure and volume thresholds required to initiate a reflex.
Phenol red (a P2X1/P2X3 antagonist; 0.1 and 1 μmol kg−1) caused a significant increase in the pressure and volume thresholds required to initiate a reflex and, at the higher dose, also caused a reduction in postinfusion isovolumetric contractions.
RO116‐6446/008 (a P2X1‐selective antagonist; 1 and 10 μmol kg−1) only caused a reduction in postinfusion isovolumetric contractions.
It is concluded that P2X1 and P2X3 receptors play a fundamental role in the micturition reflex in urethane‐anesthetized female rats. P2X3 receptor blockade raised the pressure and volume thresholds for the reflex, whereas P2X1 receptor blockade diminished motor activity associated with voiding. P2Y1 receptors may be involved in inhibition of rat detrusor tone.
The effects of purinoceptor ligands for P2X1 and/or P2X3 receptors (α,β‐meATP, IP5I, TNP‐ATP, MRS 2179, PPADS, Phenol red and RO116‐6446/008; i.v., n=4–5) and for P2Y1 receptors (PPADS, MRS 2179 and MRS 2269; i.v., n=3–5) were investigated on the distension‐evoked ‘micturition reflex’ in the urethane‐anaesthetized female rat.
α,β‐meATP (180 nmol kg−1 min−1), IP5I (10, 30 and 100 nmol kg−1), TNP‐ATP (1 μmol kg−1), MRS 2179 (1 μmol kg−1) and PPADS (17 μmol kg−1) each caused maintained bladder contractions to occur during the infusion of saline into the bladder. PPADS (17 μmol kg−1 min−1) had a similar effect when infused intravesicularly. Regular bladder contractions were not observed until the infusion of saline was halted. For IP5I, TNP‐ATP, MRS 2179 and PPADS, the magnitude of postinfusion isovolumetric contractions was significantly reduced and, for IP5I, this action was also associated with a significant reduction in urethral relaxation. Additionally, TNP‐ATP caused a significant increase in the pressure and volume thresholds required to initiate a reflex.
Phenol red (a P2X1/P2X3 antagonist; 0.1 and 1 μmol kg−1) caused a significant increase in the pressure and volume thresholds required to initiate a reflex and, at the higher dose, also caused a reduction in postinfusion isovolumetric contractions.
RO116‐6446/008 (a P2X1‐selective antagonist; 1 and 10 μmol kg−1) only caused a reduction in postinfusion isovolumetric contractions.
It is concluded that P2X1 and P2X3 receptors play a fundamental role in the micturition reflex in urethane‐anesthetized female rats. P2X3 receptor blockade raised the pressure and volume thresholds for the reflex, whereas P2X1 receptor blockade diminished motor activity associated with voiding. P2Y1 receptors may be involved in inhibition of rat detrusor tone.
British Journal of Pharmacology (2004) 142, 519–530. doi:10.1038/sj.bjp.0705790
DOI: 10.1038/sj.bjp.0705790
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