Age‐associated urethral dysfunction in urethane‐anesthetized rats. Issue 4 (15th January 2018)

• Record Type: Journal Article
• Authors: Kimura, Ryu; Miyazato, Minoru; Ashikari, Asuka; Oshiro, Takuma; Saito, Seiichi
• Is Part Of: Neurourology and urodynamics. Volume 37:Issue 4(2018:Apr.)
• Page Start: 1313
• Page End: 1319
• Publication Date: 2018-01-15
• Subjects: aging -- nitric oxide -- urethra; Urinary organs -- Periodicals; Urodynamics -- Periodicals; Urology -- Periodicals; 616.6
• DOI: 10.1002/nau.23481
• Languages: English
• ISSNs: 0733-2467

Abstract

Abstract : Aims: We aimed to investigate the age‐associated changes in movement coordination between the urinary bladder and the urethra in rats. Methods: A total of 17 female Sprague‐Dawley rats were used. The rats were divided into young (3 months old) and middle‐aged (12‐15 months old) groups. In both groups, isovolumetric cystometry and urethral perfusion pressure (UPP) measurements were performed under urethane anesthesia. After the rhythmic bladder contractions stabilized, L‐arginine, a nitric oxide (NO) substrate (100 mg/kg), was administered intravenously in both groups. Subsequently, N‐nitro‐L‐arginine methyl ester hydrochloride (L‐NAME) (50 mg/kg) was injected intravenously to inhibit NO synthase activity in both groups. Results: UPP change, defined as UPP nadir minus baseline UPP, was significantly smaller in middle‐aged rats (64%) than in young rats ( P < 0.05). The mean amplitude of high‐frequency oscillations (HFOs) of the external urethral sphincter was also significantly lower (62%) in middle‐aged rats than that in young rats ( P < 0.05). Urethral contraction during UPP change was also noted in middle‐aged rats. This urethral contraction disappeared after L‐arginine administration. UPP nadir during bladder contraction was inhibited by L‐NAME in both groups. UPP change was greater in middle‐aged rats than in young rats, and 3 out of 9 middle‐aged rats showed a detrusor‐sphincter dyssynergia pattern after L‐NAME. Conclusions: The results indicated that aging induces dysfunction in movement coordination between the urinary bladder and the urethra. Thus, age‐associated urethral dysfunctions may lead to inefficient voiding with increased post‐void residual urine volume, which is often observed in elderly populations.