Relationship between Voided Urine Volume and Urinary ATP in Healthy Volunteers

Kimio Sugaya,Saori Nishijima,Katsuhiro Ashitomi,Katsumi Kadekawa,Hideyuki Yamamoto

doi:10.4236/oju.2018.810031

Abstract

Purpose: We examined the relationship between the urinary ATP level and the desire to void, voided urine volume, and urinary osmotic pressure. Materials and Methods: The subjects were 4 healthy volunteers (2 men and 2 women) without micturition disorders who were not taking any medications and had normal urinalysis findings. Over 2 - 3 days, they urinated into a clean cup a total of 20 times. The strength of the desire to void was classified (none, slight, moderate, or strong; scored from 1 to 4, respectively) and a voiding score was assigned at each urination, along with measurement of the voided volume, urinary ATP, urinary creatinine, and urinary osmotic pressure (one man). Results: Variation of the urinary ATP/creatinine ratio was large in both male and female subjects. The urinary ATP/creatinine ratio was lower in the 2 men compared with the 2 women. This ratio showed a significant negative correlation (R2 = 0.1577 and 0.1673, both p < 0.05) with the voided urine volume in the male subjects. However, there was no relationship between the urinary ATP/creatinine ratio and the voiding score or voided urine volume in the female subjects. Conclusions: The urinary ATP level may not be a clinically useful marker of bladder pathology. Both the present study and our previous studies identified a large sex difference in the urinary ATP/creatinine ratio, and this finding may be important when considering the causes of overactive bladder (OAB) in women. The mechanism underlying the increase in urinary ATP in women should be investigated to develop new therapies for OAB.

Highlights

Adenosine triphosphate (ATP) is a major neurotransmitter in both the motor and sensory neurons of the peripheral nervous system [1] [2]
There was no relationship between the urinary ATP/creatinine ratio and the voiding score or voided urine volume in the female subjects
It is difficult to prove that urinary ATP is mainly derived from the bladder epithelium, it has been demonstrated that release of ATP from cultured epithelial cells is increased in patients with interstitial cystitis [6]

Summary

Introduction

Adenosine triphosphate (ATP) is a major neurotransmitter in both the motor and sensory neurons of the peripheral nervous system [1] [2]. In our previous study using rats, the urinary ATP level was increased after stimulation of the bladder by infusion of acetic acid, while this increase in urinary ATP was blocked by adrenergic alpha-1 receptor antagonists or anti-muscarinic agents [7] [8]. In patients with benign prostatic hyperplasia (BPH), administration of an alpha-1 receptor antagonist decreased lower urinary tract symptoms (LUTS) and reduced the urinary ATP/creatinine ratio, with improvement of LUTS being greater in patients who had a high baseline urinary ATP level. In patients with overactive bladder (OAB), an anti-muscarinic agent improved LUTS and decreased the urinary ATP/creatinine ratio, and LUTS showed more improvement when the baseline urinary ATP level was elevated. Improvement of LUTS in patients with BPH or OAB by treatment with an alpha-1 receptor antagonist or anti-muscarinic agent was related to reduction of the urinary ATP/creatinine ratio [9]. It is possible that urinary ATP could be measured as a marker of bladder pathology

Methods

Results

Conclusion