Comparative study of the contractile activity evoked by ATP and diadenosine tetraphosphate in isolated rat urinary bladder

Characterization of the urinary bladder dysfunction in renovascular hypertensive rats

AIMS

Association between arterial hypertension and urinary bladder dysfunction has been reported in humans and spontaneously hypertensive rats. However, no study exists evaluating the bladder dysfunction in conditions of renovascular hypertension. The purpose of this study was to characterize the bladder dysfunction in two kidney-one clip (2K-1C) hypertensive rats.

METHODS

A silver clip was placed around the renal artery of male Wistar rats. After 8 weeks, cystometric study, concentration-response curves to contractile and relaxant agents, frequency-dependent contractions, histomorphometry, muscarinic M(2) /M(3) mRNA expression and cyclic AMP measurements were performed.

RESULTS

2K-1C rats showed enhanced bladder volume, wall thickness and smooth muscle density. 2K-1C rats also exhibited increases in bladder capacity and non-void contractions, and decreases in the inter-contraction intervals. In isolated detrusor smooth muscle (DSM), contractions to carbachol and electrical-field stimulation (EFS) were significantly greater in 2K-1C rats. The Rho-kinase inhibitor Y27632 (10 µM) significantly reduced the carbachol-induced contractions in SHAM and 2K-1C rats, but DSM remained overactive in 2K-1C rats in presence of Y27632. Concentration-dependent contractions to the P2X receptor agonist α,β-methylene ATP, KCl and extracellular Ca(2+) did not change between SHAM and 2K-1C groups. In 2K-1C rats, isoproterenol, metaproterenol and BRL 37-344 (non-selective, β(2) - and β(3) -selective adrenoceptor agonists, respectively) produced significantly lower relaxations and decreased cAMP levels, whereas relaxant responses to sodium nitroprusside and BAY 41-2272 remained unchanged. Muscarinic M(3) mRNA expression receptors were higher in 2K-1C group.

CONCLUSIONS

Renovascular hypertensive rats exhibit bladder dysfunction that involves tissue remodeling and enhanced muscarinic M(3) -mediated contractions associated with reduced β-adrenoceptor-mediated signal transduction.

Uridine adenosine tetraphosphate induces contraction and relaxation in rat aorta

Uridine adenosine tetraphosphate (Up(4)A) has been recently reported as an endothelium-derived vasoconstrictor and plasma levels of this dinucleotide are increased in juvenile hypertensive subjects. This study aimed to evaluate the vascular actions of Up(4)A, typify the putative purinergic receptors that might mediate these effects and characterize the intracellular signaling pathways that may govern Up(4)A responses. Up(4)A induced a modest endothelium-dependent relaxation of rat aortic rings contracted with phenylephrine. From baseline, Up(4)A induced concentration-dependent contractions that were significantly potentiated by endothelium removal or nitric oxide synthase inhibition. The contractile response induced by Up(4)A was not tachyphylactic and was significantly reduced in the presence of P1 or P2X receptor antagonists, L-type Ca(2+) channel blocker and Rho-kinase inhibitor. Up(4)A-induced contraction apparently involves superoxide anion formation since it was significantly reduced by treatment with apocynin or tempol. This study presents the unique findings that the endogenous compound Up(4)A is able to induce relaxation in addition to contraction of rat aorta. Up(4)A-induced contraction is modulated by nitric oxide production, mediated by P1 and P2X receptor activation, and involves L-type Ca(2+) channels, Rho-kinase pathway and superoxide formation.

Contractile activity of ATP and diadenosine tetraphosphate on urinary bladder in the rat: role of A1- and P2X-purinoceptors and nitric oxide

1. Both adenosine-5'-triphosphate (ATP) and diadenosine tetraphosphate (AP4A) produced a dose-dependent contraction of the isolated rat urinary bladder rings. AP(4)A dose-response curve was to the left of that of ATP, and maximum response was greater than that produced by ATP. 2. 8-cyclopentyl-1,3-dipropylxanthine (DPCPX), the A1-purinergic receptor blocker (0.01 mm) significantly inhibited the ATP- and AP4A-induced contractions at the whole dose range. The inhibition was between 31-41%, and 15-25% for ATP and AP4A respectively. 3. Pyridoxal phosphate 6-azophenyl-2',4'-disulphonic acid (PPADS), the P2X-purinoceptor antagonist (0.01 mm) potently inhibited the bladder contractions in response to ATP and AP4A by around 75-80%. 4. The nitric oxide (NO) precursor L-arginine reduced the bladder contractile response to ATP by about 22-41% and that of AP4A to a lesser extent by around 20-32%. 5. The nitric oxide synthase inhibitor, N(G)-nitro-L-arginine methyl ester (L-NAME, 0.1 mM), did not produce any significant effect on ATP except for a weak inhibition of about 14% at the lowest dose of ATP. The contractions in response to AP4A were only slightly reduced by L-NAME by about 20%. 6. In conclusion, the contractile response of the bladder to ATP and to the dinucleotide AP4A is mediated mainly through P2X-purinoceptors and A1-purinergic receptors. In the detrusor muscle, NO donation possesses an inhibitory effect on ATP-mediated contractility more than that produced by the dinucleotide AP4A.

Contractile activity of ATP and diadenosine tetraphosphate on urinary bladder in the rats: role of superoxide anion and urothelium

Both ATP and diadenosine tetraphosphate (AP(4)A) produced a dose-dependent contraction of rat isolated urinary bladder rings. The AP(4)A dose-response curve was to the left of that of ATP, and the maximum response was greater than that produced by ATP. Mechanical removal of the urothelium increased the contractile response to ATP by between 53% and 71%, and that to AP(4)A by 42% (at highest AP(4)A concentration) to 68% at lower concentration. Inhibition of Cu/Zn superoxide dismutase with diethylthiocarbamate (DETCA, 5 mm) significantly reduced the ATP-evoked contraction by 31% (at high ATP concentration) to 40% at low ATP concentration. Similarly, the AP(4)A-induced contractions were significantly decreased by 27% at low AP(4)A level to 38% at higher concentrations. Induction of exogenous superoxide anion stress by the use of the superoxide anion generator, pyrogallol (0.5 mm), significantly decreased both ATP- and AP(4)A-induced contractions of the rat urinary bladder over the whole dose range. Contractile responses to ATP decreased by 36-40%, and those to AP(4)A by 44-49%. In conclusion, the urinary bladder urothelium exerts an inhibitory control over the purinergic contractility produced by adenine mononucleotides and dinucleotides. Superoxide anion stress, whether endogenous or exogenous, attenuates the ATP-induced as well as AP(4)A-induced contractility.

Perinephric urinoma secondary to neurogenic bladder with vesicoureteral reflux: report of an adult case

We report a case of infectious perinephric urinoma in a 73-year-old woman who had a neurogenic bladder with vesico-ureteral reflux. The patient was admitted to our emergency room with right lumbago and high fever. Ultrasounds and computed tomography demonstrated a right large perinephric cystic mass, bilateral hydronephrosis and much residual urine. Percutaneous drainage of the cystic mass was performed with an indwelling urethral catheter. The content of the mass was urine infected with Escherichia coli. Antibiotic therapy was performed successfully and we then examined the cause of the urinoma. A urodynamic study demonstrated a low-compliance small bladder and detrusor-sphincter dyssynergia. A voiding cystourethrogram revealed right grade III vesicoureteral reflux. The patient was unable to be cleared with intermittent catheterization and had an indwelling urethral catheter inserted. In 1 year, the voiding cystourethrogram showed no vesicoureteral reflux and the patient was well with no evidence of recurrent urinoma without the urethral catheter. There have been only two reported cases of urinoma caused by neurogenic bladder with vesico-ureteral reflux in children and this is the first case reported in an adult.

Effect of the flavonoid galangin on urinary bladder rat contractility in-vitro

Galangin is a flavanol with several biological activities. We have evaluated the effect of galangin on the contractile response elicited by electrical field stimulation (EFS) in the rat isolated urinary bladder. Galangin (10(-8)-10(-4) M) produced a concentration-dependent inhibition of the EFS contractile response without modifying the contractions produced by exogenous acetylcholine (10(-6) M). Blockade of adrenergic and cholinergic nerves with a combination of atropine (10(-6) M), phentolamine (10(-6) M) and propranolol (10(-6) M) or blockade of tachykinin NK1 and NK2 receptors with SR140333 (10(-7) M) and SR48968 (10(-6) M) did not modify the inhibitory effect of galangin. However, verapamil (10(-7) M) significantly reduced the inhibitory effect of galangin. It is concluded that the galangin inhibits EFS-induced contractions of the rat urinary bladder by acting on L-type calcium channels on presynaptic nerves.