Hypothesis / aims of study
To analyze the difference in urodynamic evaluation in rats with slight, deep anesthesia and wakefulness, providing evidence for low urinary tract functional animal study.
Study design, materials and methods
Thirteen male Sprague-Dawley (SD) rats were involved in this study. They were done operation of cystostomy, The bladder stoma was passed subcutaneously to the back of the neck and exteriorized. In different anesthetic conditions and in awake condition the bladder stoma was connected via a three-way stopcock to a pressure transducer for recording intravesical pressure and a syringe pump for infusing saline. We recorded the urodynamic parameters contained bladder basal pressure, voiding interval, voiding stage maximum detrusor pressure, bladder functional capacity, bladder compliance and voiding stage maximum bladder pressure. The cystometry way conform SCI’s basic rules of cystometrography. The paired T test was used for the statistical analysis with P<0.05 considered to indicate statistical significance.
The results of rat’s cystometry were different in these three conditions. In the deep anesthetic condition the rat’s bladder couldn’t contract, when up to some volume there would be overflow incontinence and the bladder leakage pressure( BLPP) is 33.101±7.189cmH2O.The bladder compliance in deep anesthetic condition （0.0174±.0126cmH2O/ml）is smaller than in slight anesthetic condition（0.0894±0.0922 cmH2O/ml） and awake condition（0.104±0.136cmH2O/ml）(P0.05). The bladder had transient contraction in slight anesthetic condition and awake condition, and the rats could urinate by themselves, but their voiding stage maximum detrusor pressure , voiding stage maximum bladder pressure, voiding interval and functional bladder capacity in slight anesthetic condition all (19.512±6.002cmH2O ,32.027±6.309cmH2O, 156.306±81.327s,0.261±0.136ml) were smaller than in awake condition(27.360±6.284cmH2O 38.144±7.974cmH2O,237.057±124.388s,0.389±0.202ml) (P0.05).The bladder compliance and bladder basal pressure were not statistically significant in slight anesthetic condition and awake condition.
Interpretation of results
Cystometry in rat is very important in checking rats’ bladder function,it is the gold standard in checking bladder function. There are two common cystometry ways: One is anesthetic condition cystometry, another is awake condition cystometry, so knowing the difference of this two ways is very important to us to analyze the rat’s urodynamic results for our animal experiments.
In present experiment the voiding phrase maximum bladder pressure and detrusor pressure in awake condition were higher than in anesthetic condition. It might indicate the anesthesia drug had impact on the bladder function, Maybe it can reduce detrusor contraction force through some way, maybe it through affect nerval system, maybe it’s through affect detrusor, but the exactly mechanism is unknown. This result remind us when we do cystometry to rats in anesthetic condition we should consider the drug’s effect on bladder. In deep anesthetic condition the bladder was paralyzed, it couldn’t contract, it’s a little similar with the isolated bladder, we can use this condition in some specific condition, for example when we study the bladder myogenic mechanism,we can use this condition. The voiding interval in slight anesthetic condition is smaller than in awake condition, maybe it’s because the residual urine volume is more in anesthetic condition than in awake condition. We didn’t check the biggest bladder capacity, maybe the biggest bladder capacity has no significant difference in anesthetic and awake condition, in this case the voiding interval in slight anesthetic condition will be smaller. The bladder compliance has no significant difference in slight anesthetic condition and awake condition, but in deep anesthetic condition it is smaller than the other two conditions, it maybe indicate innervation has impact on bladder compliance. The bladder basal pressure were not statistically significant in slight anesthetic condition and awake condition, it’s accordant to the compliance result in this two condition, it’s because the bladder compliance has a close relationship with bladder basal pressure.