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Potential vascular mechanisms in an ex vivo functional pig bladder model
Author(s) -
Anele Uzoma A.,
Ratz Paul H.,
Colhoun Andrew F.,
Roberts Sydney,
Musselman Ryan,
Vince Randy A.,
Speich John E.,
Klausner Adam P.
Publication year - 2018
Publication title -
neurourology and urodynamics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.918
H-Index - 90
eISSN - 1520-6777
pISSN - 0733-2467
DOI - 10.1002/nau.23710
Subject(s) - perfusion , ischemia , medicine , ex vivo , pathophysiology , in vivo , oxygenation , hemodynamics , blood flow , autoregulation , cardiology , blood pressure , biology , microbiology and biotechnology
Aims Chronic ischemia is a recognized factor in the pathophysiology of underactive bladder (UAB). Although relative ischemia (ie, low blood flow) is known to occur during filling, little is known regarding the pathophysiology that leads to UAB. Therefore, we developed an ex vivo functional porcine model to investigate the role of transient ischemia and whether autoregulation, a mechanism that maintains tissue oxygenation in certain vital organs, also exists in the bladder. Methods Using bladders from slaughtered pigs, we prepared an isolated perfused model where we studied the effects of bladder perfusion flow rate on perfusion pressure and tissue oxygenation during the filling phase. Bladders were perfused at an initial flow rate of 20 mL/min and then clamped in a sequentially decreasing stepwise manner down to no flow and back to the initial flow rate. Results We found a linear relationship between flow rate and perfusion pressure until the flow rate decreased below 5 mL/min at which point the vascular resistance decreased; however, tissue pO 2 remained stable after an initial decline. Conclusions These findings suggest that there may be an intrinsic autoregulatory mechanism in the bladder that allows it to undergo cyclic episodes of relative ischemia during its normal function. Factors that overcome this mechanism such as complete or chronic ischemia may be critical in the progression to detrusor underactivity and thereby highlight the importance of intervention during the early phases of this disease process.