URINARY-BLADDER BLOOD-FLOW CHANGES DURING THE MICTURITION CYCLE IN A CONSCIOUS PIG MODEL

Purpose: To develop a method using laser Doppler flowmetry in consciou s pigs, which allows the accurate simultaneous measurement of cystomet ric and cardiovascular parameters together with changes in vesical blo od flow. The animal model was then used to investigate the changes in blood flow in tile urinary bladder which occur during the micturition cycle. Materials and Methods: Seven large white female pigs were subje cted to chronically implanted vascular access and urodynamic catheters as well as an intramural vesical laser Doppler probe. The animals und erwent repeated conscious urodynamics with simultaneous measurement of cardiovascular, urodynamic and vesical blood flow parameters. Results : The model shows both compliant and low-compliance behavior and allow s greater investigation of the effects of intravesical pressure on blo od flow. Blood flow is not altered, during compliant filling and voidi ng transiently decreases flow to 38% of resting levels, with a rapid r eturn to normal, Low-compliance filling results in a progressive fall in blood flow to a minimum of 45% of normal. At all times an inverse r elationship between intravesical pressure and blood flow is maintained . Conclusions: The pig model proved tu be well suited to the experimen tal conditions and provided reproducible results, The principal determ inant of blood flow within the wall of the bladder is the pressure wit hin its lumen. During normal filling the blood supply of the bladder i s able to adapt to the large increase in surface area which occurs, ma intaining blood flow until the pressure increases.