Circadian Rhythms of Renal Hemodynamics in Unanesthetized, Unrestrained Rats

Pons, Marianne; Tranchot, J.; L’Azou, B; Cambar, J.

doi:10.3109/07420529409057246

Cited by 28 publications

(24 citation statements)

References 31 publications

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“…Furthermore, bladder filling rate, and thus LUT output, depends upon the rate of urine production by the kidney. The diurnal variation in voiding frequency and volume reflects diurnal variation in glomerular filtration rate, bladder capacity, and autonomic function . Thus, many other factors contribute to voiding that were not assessed directly in the present study.…”

Section: Discussionmentioning

confidence: 88%

“…The diurnal variation in voiding frequency and volume reflects diurnal variation in glomerular filtration rate, bladder capacity, and autonomic function. 11,15,16 Thus, many other factors contribute to voiding that were not assessed directly in the present study. The strength of the relationship between void size and inter-void interval likely reflects the contribution of a number of these factors, including: the rate of production of urine (reflecting in large part glomerular filtration rate), which dictates how fast the bladder fills; bladder compliance (influenced by tissue biomechanics and autonomic tone) which affects bladder capacity; and the sensitivity of afferent and central pathways involved in transduction, transmission and integration of sensory information that contribute to setting the threshold for reflex control of bladder activity.…”

Section: Discussionmentioning

confidence: 92%

See 1 more Smart Citation

Contribution of the external urethral sphincter to urinary void size in unanesthetized unrestrained rats

LaPallo

Wolpaw

Chen

et al. 2015

Neurourology and Urodynamics

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Aims In anesthetized rats, voiding is typically associated with phasic activation (bursting) of the external urethral sphincter (EUS). During spontaneous voiding in unanesthetized, unrestrained rats, EUS bursting is the most common form of EUS activity exhibited, but it is not necessary for productive voiding to occur. The aim of the present study was to determine which aspects of EUS activity contributed to void size during bursting and non-bursting voiding in conscious, freely moving rats. Methods Female rats were implanted with electrodes adjacent to the EUS for recording electromyographic activity (EMG). EUS EMG recordings were performed during 24-hr sessions in a metabolic cage while voided urine was continuously collected and weighed. Results Void size was positively correlated with the duration of the intra-burst silent and active periods and variables reflecting the overall intensity and duration of bursting, particularly at lower frequencies within the 3–10 Hz range of EUS bursting. In addition, void size was inversely related to the frequency of bursting and to the average EMG amplitude during voiding, both in voids with and without bursting. Conclusions EUS bursting contributes to productive voiding when bursting is present. Lower bursting frequencies elicit more productive voiding than do higher frequencies. In the absence of bursting, the association of increased void size with smaller average EUS EMG amplitude suggests that conscious rats can perform synergic voiding (i.e., bladder contraction with EUS relaxation) that is comparable to that seen in humans and other typically non-bursting species.

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Section: Discussionmentioning

confidence: 88%

Section: Discussionmentioning

confidence: 92%

Contribution of the external urethral sphincter to urinary void size in unanesthetized unrestrained rats

LaPallo

Wolpaw

Chen

et al. 2015

Neurourology and Urodynamics

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“…Drug excretion is influenced by kidney functions such as renal blood flow, glomerular filtration rate, and urine volume. Renal blood flow exhibits a significant circadian rhythm: it shows a peak during the active phase, which is twice the level of the peak seen during the resting phase in human and rats (40,41). Circadian oscillations in glomerular filtration rate are apparently synchronized with those of renal blood flow and systemic hemodynamics, with a 50% change at the day-night transition (42).…”

Section: Pharmacokineticsmentioning

confidence: 86%

Chrono-biology, Chrono-pharmacology, and Chrono-nutrition

Tahara¹,

Shibata²

2014

J Pharmacol Sci

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Molecular mechanisms of the circadian clock systemThe circadian clock system has been widely maintained in many species, from prokaryotes to mammals. "Circadian" means "around [a] day" in Latin, and therefore "circadian rhythm" refers to a cycle of approximate 24 h. The earth rotates once every 24 h, and the circadian system has evolved to adjust functions and behavior to this cycle in order to efficiently utilize sunlight for photosynthesis in the case of plants and cyanobacteria and to obtain food in the case of animals. One of the most important features of our circadian system is that circadian clocks can endogenously maintain time under constant darkness and without external stimuli, suggesting that our body has its own internal clocks. In 1972, Moore and Eichler (1) investigated the effects of destroying the suprachiasmatic nucleus (SCN) in the rat hypothalamus. Their results revealed the loss of sleep-wake cycles and corticosterone rhythms. Since then, the SCN is regarded as the location of the master clock system in mammals. The SCN receives light-dark information directly through the retinal-hypothalamic tract and organizes the local clock in the peripheral tissues through multiple pathways involving neural and hormonal functions (2, 3). The molecular mechanism of the circadian system in mammals has been well studied over the past two decades. The transcriptional-translational feedback loop of the major clock genes Bmal1, Clock, Per1/2, and Cry1/2 is the main component of the circadian system (2) (Fig. 1A). Bmal1 and Clock, which are transcriptional activators, play a positive role in activating the Per and Cry genes through a specific promoter sequence known as the E-box. Per and Cry are translated into proteins in the cytoplasm and are then transported back into the nucleus after interacting with each other, and they subsequently stop their transcription by binding to BMAL1 and CLOCK. Thus, Per and Cry are rhythmically expressed over a 24-h period. This transcriptional regulation induces rhythmic expression of approximately 10% of all genes in each peripheral cell (4 -6). In addition to such transcriptional regulation of the circadian clock, post-transcriptional regulation and translational regulation have recently been reported to play important roles in maintaining circadian rhythms. Genome-wide RNA-seq and Chip-seq analyses found that only 22% of the rhythmically oscillating messenger RNAs are driven by de novo transcription, with RNA polymerase II recruitment and chromatin remodeling also exhibiting such rhythms (7). Furthermore, it was reported that the non-transcriptional redox cycle has a 24-h rhythm in Chrono-biology, Chrono-pharmacology, and Chrono-nutrition Tokyo 162-8480, Japan Received October 25, 2013; Accepted January 5, 2014 Abstract. The circadian clock system in mammals drives many physiological processes including the daily rhythms of sleep-wake behavior, hormonal secretion, and metabolism. This system responds to daily environmental changes, such as the light-dark cycle, food...

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“…They are active during the night and rest during the day, which is the opposite to humans. So diurnal rhythms of renal function in rats are reversed, that is, the peak of urinary electrolyte excretion occurs during the night‐time, and the peak of GFR and RBF occurs in active dark period (00.30 hours) …”

Section: Discussionmentioning

confidence: 99%

“…For example, studies in rats have indicated that the peak of urinary electrolyte excretion occurs at night, and glomerular filtration rate (GFR) and renal blood flow (RBF) reached a peak in active dark period (00.30 hours). [6][7][8] Previously, diurnal rhythms of renal function were thought to be caused by external factors such as dietary intake, posture, or sleep; but they have been shown to persist over long periods of time under experimental conditions in which external factors were kept constant or were manipulated in a noncircadian manner. 9 These findings indicate that in addition to the external circadian stimuli (hormones, food, food metabolites) the functional rhythms are also controlled by a self-sustained intrinsic renal clock.…”

mentioning

confidence: 99%