Age‐associated urethral dysfunction in urethane‐anesthetized rats

Abstract

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.

Changes in urethral smooth muscle and external urethral sphincter function with age in rats

“…Thus, it is thought to be part of the coordinated urethral activity during bladder contractions. Similar to our recent study (Kimura et al., 2018), the amplitude of HFOs during urethral relaxation was significantly lower in middle‐aged and aged rats than in young rats in this study. Our novel study on the triple recording of EUS‐EMG also showed bursting activity during bladder contractions with a clear AP and SP in young rats, an unclear AP and SP in middle‐aged rats, and no SP in aged rats.…”

“…Urethral smooth muscle relaxation is crucial for efficient voiding. Similar to the findings of our recent study (Kimura et al., 2018), the change in UPP during bladder contractions was significantly decreased in middle‐aged (i.e., 12‐month) rats, as compared to that in young rats in this study. We also confirmed the decreased UPP change in aged rats (24 months) and obtained the same results.…”

“…Therefore, as the next step, we examined the time‐course changes in UPP using EUS‐EMG under isovolumetric bladder conditions and urethane anesthesia. Second, similar to our recent data (Kimura et al., 2018), the change in UPP during bladder contractions was significantly decreased in both middle‐aged and aged rats when compared to that in young rats, suggesting impairment in urethral smooth muscle relaxation with age. Third, EUS‐EMG revealed bursting activity during bladder contractions with a clear AP and SP in young rats but an unclear AP and SP in aged rats, suggesting impairment in EUS activity with age.…”

“…We also confirmed the decreased UPP change in aged rats (24 months) and obtained the same results. In our recent study, urethral contraction during urethral relaxation was noted in middle-aged rats, which disappeared after treatment with Arg, an NO substrate (Kimura et al, 2018). Alexandre et al (Alexandre et al, 2014) reported that NO donor-mediated urethral smooth muscle relaxation was impaired in obese mice, and this impairment could be reversed by BAY 60-2770, a soluble guanylyl cyclase activator.…”

“…The pumping activity of the EUS does not occur in humans (Maggi et al., 1986; Miyazato et al., 2008; Nishizawa et al., 1984). In our recent study, middle‐aged (i.e., 12–15 month old) rats exhibited an impairment in urethral smooth muscle relaxation and a reduction in the HFOs of the EUS (Kimura et al., 2018). Nonetheless, age‐related changes in two different urethral mechanisms and the relationship between them have not been understood.…”