Urinary ATP Levels Are Controlled by Nucleotidases Released from the Urothelium in a Regulated Manner

Adenosine 5′-triphosphate (ATP) is released in the bladder lumen during filling. Urothelial ATP is presumed to regulate bladder excitability. Urinary ATP is suggested as a urinary biomarker of bladder dysfunctions since ATP is increased in the urine of patients with overactive bladder, interstitial cystitis or bladder pain syndrome. Altered urinary ATP might also be associated with voiding dysfunctions linked to disease states associated with metabolic syndrome. Extracellular ATP levels are determined by ATP release and ATP hydrolysis by membrane-bound and soluble nucleotidases (s-NTDs). It is currently unknown whether s-NTDs regulate urinary ATP. Using etheno-ATP substrate and HPLC-FLD detection techniques, we found that s-NTDs are released in the lumen of ex vivo mouse detrusor-free bladders. Capillary immunoelectrophoresis by ProteinSimple Wes determined that intraluminal solutions (ILS) collected at the end of filling contain ENTPD3 > ENPP1 > ENPP3 ≥ ENTPD2 = NT5E = ALPL/TNAP. Activation of adenylyl cyclase with forskolin increased luminal s-NTDs release whereas the AC inhibitor SQ22536 had no effect. In contrast, forskolin reduced and SQ22536 increased s-NTDs release in the lamina propria. Adenosine enhanced s-NTDs release and accelerated ATP hydrolysis in ILS and lamina propria. Therefore, there is a regulated release of s-NTDs in the bladder lumen during filling. Aberrant release or functions of urothelial s-NTDs might cause elevated urinary ATP in conditions with abnormal bladder excitability.

Aging-related severe hypertension induces detrusor underactivity in rats

AIMS

Aging is an obvious risk factor for detrusor underactivity. We investigated the effects of aging on bladder function in spontaneously hypertensive rats.

MAIN METHODS

Male spontaneously hypertensive rats and Wistar Kyoto rats (used as normotensive controls) at the ages of 18, 36, 54, or 72 weeks were used. Bladder weight, blood pressure, bladder blood flow, and urodynamic and renal parameters were measured. Additionally, detrusor thickness and renal histology were evaluated.

KEY FINDINGS

In spontaneously hypertensive rats, significant increases were observed in bladder weight/body weight ratio, blood pressure, detrusor thickness, intercontraction interval, urine output, serum creatinine, and renal glomerular and tubular scores, and decreases in bladder blood flow and urine osmolality at 72 weeks as compared to those at 18 weeks. In spontaneously hypertensive rats, significant increases were observed in single voided volume, post voiding residual urine volume, and bladder capacity, with decrease in voiding efficiency were observed at 54 or 72 weeks than at 18 weeks. However, there were no significant differences in blood pressure, urodynamic and renal parameters, detrusor thickness and renal histology among Wistar Kyoto rats of different ages.

SIGNIFICANCE

In spontaneously hypertensive rats, aging induces significant increases in blood pressure, single voided volume, post voiding residual urine volume, intercontraction intervals and urine output, and decreases in voiding efficiency and bladder blood flow indicative of detrusor underactivity. Aging-related severe hypertension could induce voiding dysfunction such as detrusor underactivity via severe bladder ischemia and polyuria. Aged spontaneously hypertensive rats may be useful animal models for detrusor underactivity.

Is there room for behavioral and modifiable health-related targets in the lower urinary tract symptoms' scenario

PURPOSE

To better understand potential modifiable risk factors guiding preventive interventions against lower urinary tract symptoms (LUTS).

METHODS

A prospective cross-sectional study, including healthy men aged 40-70 years under routine urological evaluation, measured the strength of association between the International Prostate Symptom Score (IPSS) and socio-demographic, lifestyle, and health-related factors using logistic and linear regression adjusted for confounding factors. Men with urethral or prostate surgery were excluded.

RESULTS

Among 743 men, mean age 59.64 ± 9.66, 22.6% reported moderate, and 5.0% severe LUTS. The adjusted odds of severe LUTS increased with: increasing age (OR = 1.07, 95% CI = 1.05-1.09, p < .0001), increasing prostate volume (OR = 1.02, 95% CI = 1.01-1.04, p = .004), decreasing education (tertiary qualification, no versus yes, OR = 2.34; 95% CI = 1.16-4.70; p = .0133), delayed ejaculation (yes versus no, OR = 2.63, 95% CI = 1.43-4.83, p < .0001), and increasing blood pressure (systolic ≥130 mmHg, OR = 2.03, 95% CI = 1.44-2.86, p < .0001 or diastolic ≥85 mmHg, OR = 1.47, 95% CI = 1.03-2.10, p = .0345); severe LUTS decreased with: increasing the weekly sexual frequency (OR = 0.80, 95% CI = 0.69-0.91, p = .0012) and increasing HDL cholesterol (OR = 0.98, 95% CI = 0.97-0.99, p = .037). Odds were not significant for age of sexual initiation, precocious ejaculation, masturbatory pattern, physical activity, smoking, alcohol consumption, penile length (objective and subjective), abdominal circumference, obesity, comorbid conditions, metabolic syndrome, serum glycaemia, testosterone, SHBG, PSA, and estradiol.

CONCLUSIONS

One in every four men under routine urological evaluation who considered themselves healthy present moderate and severe LUTS. Modifiable behavioral (education, sexual frequency, and ejaculation) and health-related (blood pressure and HDL cholesterol) targets were identified for future interventional studies and potential preventive actions and patient counseling.

Chronic Pelvic Ischemia: Contribution to the Pathogenesis of Lower Urinary Tract Symptoms (LUTS): A New Target for Pharmacological Treatment?

The incidence of lower urinary tract symptoms, including overactive bladder (OAB), is continuing to rise, and is associated with a negative impact on quality of life and a heavy economic burden. A major risk factor for OAB is advancing age. The etiology of OAB is multifactorial and appears to involve myogenic, neurogenic, and urotheliogenic factors. In this article, we review the strengthening preclinical evidence supporting the contribution of chronic pelvic ischemia to the pathogenesis of OAB. In animal models, chronic ischemia induced by arterial injury and a high-fat diet upregulates markers of oxidative stress and proinflammatory cytokines in the urothelium and lamina propria, and leads to increased expression of nerve growth factor. These processes result in increased afferent activity and an increased frequency of micturition, reflecting a state of bladder hyperactivity. In severe, prolonged cases, bladder overactivity may develop into underactivity. Antimuscarinic therapies are the mainstay of OAB treatment, but their usefulness is limited by modest efficacy and troublesome side-effects. Our increasing understanding of the contribution of chronic ischemia to OAB is leading toward novel therapeutic options targeting chronic pelvic ischemia and its morphological, functional, and oxidative consequences. Preclinical trials have demonstrated encouraging results with α1 -adrenoreceptor blockade, phosphodiesterase type 5 inhibition, β3 -adrenoreceptor agonism, free radical scavenging, and stem cell therapy, in preventing morphological, biochemical and functional changes induced by chronic bladder ischemia.

Detrusor Underactivity: The Current Concept of the Pathophysiology

Based on evidence from available literature, we review the pathophysiology of detrusor underactivity (DU). DU is likely to be multifactorial. Aging reduces detrusor activity, but other concomitant causes may aggravate this condition, resulting in decrease of detrusor contractility. Impaired detrusor contractility has been regarded as a major etiologic factor of DU. However, a more complex pathology has been proposed. As contributing factors to DU, we discuss disturbances of the sensory afferent side of the micturition reflex, the central nervous system (CNS) and the efferent side of the reflex, including nerves and the detrusor muscle. Particularly, dysfunction of afferent nerves in the bladder and urethra may play a crucial role in the pathogenesis of DU. In addition, recent studies suggest that chronic bladder ischemia and resultant oxidative stress cause detrusor overactivity progressing to DU and inability to empty the bladder.