title: Diurnal variation in urodynamics of rat.
abstract: In humans, the storage and voiding functions of the urinary bladder have a characteristic diurnal variation, with increased voiding during the day and urine storage during the night. However, in animal models, the daily functional differences in urodynamics have not been well-studied. The goal of this study was to identify key urodynamic parameters that vary between day and night. Rats were chronically instrumented with an intravesical catheter, and bladder pressure, voided volumes, and micturition frequency were measured by continuous filling cystometry during the light (inactive) or dark (active) phases of the circadian cycle. Cage activity was recorded by video during the experiment. We hypothesized that nocturnal rats entrained to a standard 12:12 light:dark cycle would show greater ambulatory activity and more frequent, smaller volume micturitions in the dark compared to the light. Rats studied during the light phase had a bladder capacity of 1.44+/-0.21 mL and voided every 8.2+/-1.2 min. Ambulatory activity was lower in the light phase, and rats slept during the recording period, awakening only to urinate. In contrast, rats studied during the dark were more active, had a lower bladder capacities (0.65+/-0.18 mL), and urinated more often (every 3.7+/-0.9 min). Average bladder pressures were not significantly different between the light and dark (13.40+/-2.49 and 12.19+/-2.85 mmHg, respectively). These results identify a day-night difference in bladder capacity and micturition frequency in chronically-instrumented nocturnal rodents that is phase-locked to the normal circadian locomotor activity rhythm of the animal. Furthermore, since it has generally been assumed that the daily hormonal regulation of renal function is a major driver of the circadian rhythm in urination, and few studies have addressed the involvement of the lower urinary tract, these results establish the bladder itself as a target for circadian regulation.
authors.affiliation: Catamount Research & Development Company, St Albans, Vermont, United States of America.
authors.forename: Gerald M
authors.initials: GM
authors.lastname: Herrera
authors.forename: Andrea L
authors.initials: AL
authors.lastname: Meredith
mesh_terms: D000818:Animals; D002940:Circadian Rhythm / Q000502:physiology*; D019411:Clinical Laboratory Techniques; D051381:Rats; D017207:Rats, Sprague-Dawley; D014563:Urodynamics / Q000502:physiology*
references.citation: J Neurosci. 2004 Sep 1;24(35):7604-13
references.pmid: 15342726
references.citation: Obstet Gynecol. 1984 Nov;64(5):657-60
references.pmid: 6387558
references.citation: J Urol. 2007 Dec;178(6):2626-9
references.pmid: 17945293
references.citation: Am J Physiol Regul Integr Comp Physiol. 2006 Jun;290(6):R1697-706
references.pmid: 16439667
references.citation: Urology. 2002 Nov;60(5 Suppl 1):28-32; discussion 32
references.pmid: 12493348
references.citation: Radiat Res. 1978 Sep;75(3):649-59
references.pmid: 724992
references.citation: J Auton Nerv Syst. 1999 Sep 24;77(2-3):73-82
references.pmid: 10580289
references.citation: Nature. 2002 Aug 29;418(6901):935-41
references.pmid: 12198538
references.citation: Anesthesiology. 2009 Jun;110(6):1305-15
references.pmid: 19417612
references.citation: Am J Obstet Gynecol. 2005 May;192(5):1682-6
references.pmid: 15902177
references.citation: Nephrol Dial Transplant. 1994;9(9):1330-3
references.pmid: 7816301
references.citation: J Clin Invest. 1951 Nov;30(11):1191-9
references.pmid: 14888696
references.citation: J Physiol. 1989 Jan;408:67-76
references.pmid: 2778742
references.citation: J Urol. 1992 Nov;148(5):1615-20
references.pmid: 1433577
references.citation: Neurourol Urodyn. 2000;19(1):87-99
references.pmid: 10602250
references.citation: J Urol. 1992 Jul;148(1):183-7
references.pmid: 1613867
references.citation: Proc Natl Acad Sci U S A. 2009 Sep 22;106(38):16523-8
references.pmid: 19805330
references.citation: J Hypertens. 1997 Apr;15(4):401-10
references.pmid: 9211175
references.citation: Eur J Pediatr. 2007 Jun;166(6):579-84
references.pmid: 17043843
references.citation: Urol Int. 1997;58(3):153-9
references.pmid: 9188136
references.citation: J Biol Rhythms. 1993 Fall;8(3):179-88
references.pmid: 8280907
references.citation: Naunyn Schmiedebergs Arch Pharmacol. 1997 Jun;355(6):774-8
references.pmid: 9205963
references.citation: Arch Gynecol Obstet. 2007 Apr;275(4):223-9
references.pmid: 17021774
references.citation: Am J Vet Res. 1973 May;34(5):665-8
references.pmid: 4703511
references.citation: Neurourol Urodyn. 2008;27(4):324-9
references.pmid: 17849479
references.citation: Cell. 2008 Sep 5;134(5):728-42
references.pmid: 18775307
references.citation: BJU Int. 2004 May;93(7):1005-8
references.pmid: 15142152
references.citation: Neth J Med. 1985;28(10):416-23
references.pmid: 3908950
references.citation: Neurourol Urodyn. 2001;20(3):287-95
references.pmid: 11385695
references.citation: J Urol. 1996 Jul;156(1):233-6
references.pmid: 8648813
references.citation: Chronobiol Int. 2006;23(1-2):201-15
references.pmid: 16687294
references.citation: Medicine (Baltimore). 1964 Sep;43:547-92
references.pmid: 14210938
references.citation: J Biol Rhythms. 2001 Jun;16(3):196-204
references.pmid: 11407779
references.citation: J Lab Clin Med. 1992 Sep;120(3):400-10
references.pmid: 1517687
references.citation: Curr Urol Rep. 2003 Oct;4(5):362-6
references.pmid: 14499058
references.citation: J Physiol. 1951 May;113(4):528-36
references.pmid: 14851256