A Method For Measuring The Vascular Sinusoids Pressure Of Urethral Wall In Female Canines

Objective: To describe a method for measuring the vascular sinusoids pressure(VSP) of urethral wall in female canines.Methods: A total of 10 adult healthy female canines were used for this study,aged 2～3years and weighed 8～10Kg.The urinary bladder,urethral meatus were exposed under intravenous pentobarbital anesthesia and cannulated for measuring the intra bladder pressure(IBP),intra urethral pressure(IUP)at the high urethral pressure zone and VSP within the distal urethral wall.All the tube systems were calibrated and set to the atmospheric pressure at the urethral meatus level(set as 0 cm H2O)and then all measuring tubes were inserted in the bladder to verify the equivalence of pressure transmission of all three tube systems.Then the IBP,IUP and VSP were recorded and digitized synchronously using a multiple-channel electrophysiological recording system at rest and stress status respectively.The intra tissue pressures of rectus abdominis and detrusor bladder tissues were recorded with the VSP system being inserted into these tissues,with or without pressing the bladder respectively.Subsequently,heparin sodium ink mixture solution was infused into the VS via the VSP measuring tube,and the whole urethra and bladder were removed en block for frozen section.Sinusoidal ink filling and staining was examined for providing morphological evidence for the accuracy of the VSP measuring system.Results: The VSP measuring system established in the present study have obtained a reliable static baseline pressure at rest status and sensitive synchronous changes with IBP and IUP at stress status.In 10 female canines,VSP、IUP、IBP were 12.27±3.51 cm H2O、21.02±3.83 cm H2O、9.10±2.81 cm H2 O,IUP/VSP and IUP/IBP were 1.86±0.64、2.74±1.57 respectively at rest status.At stress status,VSP,IUP and IBP were 17.80±4.50 cm H2O、52.01±7.47 cm H2 O 、43.05±6.41 cm H2 O,IUP/VSP and IUP/IBP were 3.08±0.81、1.22±0.18 respectively.The pressure curves of the rectus abdominis,bladder detrusor tissue and subcutaneous tissue pressure shown as a rising straight line with a certain slope,which are independent of the rest and stress status of the bladder.The submucosal vascular sinusoids stained with ink were observed in each urethral zone,providing direct morphological evidence that the VSP obtained in this present study is the intra-sinusoidal pressure of the urethral submucosal wall.Conclusions: In this study,a method of direct measuring VSP of the urethral wall in female canine was successfully established for the first time.This method may play role in further investigation of the vascular components in urethral wall and its physiological role in urethral closure mechanisms.