Xenon tissue/blood partition coefficient for pig urinary bladder

Blood flow rate and total blood flow related to length density and total length of blood vessels in mini-pig urinary bladder after chronic outflow obstruction and after recovery from obstruction

Chronic partial bladder outlet obstruction was created in mini-pigs by implanting a 6-7 mm ring around the proximal urethra. After a median obstruction period of 63 days the ring was removed, and after a median recovery period of 60 days the animals were sacrificed. At each study occasion the blood flow rate (ml per 100 g per min) was measured by washout of locally injected 133Xe in the bladder wall and the washout curves analyzed by the corrected initial slope method. Stereological estimation of length density and total length of blood vessels in the bladder were performed. The results can be summarized as follows: (1) no differences in the blood flow rate at the time of ring implantation, obstruction, or recovery, (2) no decrease in the blood flow rate in normal bladders after bladder distension, (3) a significant decrease in blood flow rate in obstructed bladders after distension, (4) a 6-fold increase in total bladder blood flow after obstruction, (5) an unchanged blood flow per length of blood vessels per min during the study, (6) no changes in length densities of blood vessels during the study, and (7) a 7-fold increase in total length of blood vessels after obstruction and reversion to control level after recovery. The unchanged blood flow per length of vessels implies that capillary proliferation matched the increased bladder mass during the study.

Rate of urinary bladder blood flow evaluated by 133Xe washout and radioactive microspheres in pigs

Urinary bladder blood flow as measured by the washout of locally injected 133Xe and by the simultaneously performed radioactive microsphere reference-sample method was studied in pigs. The washout curves were analyzed according to the initial slope, the corrected initial slope and the total curve. The corrected-initial-slope flow rates were not statistically significantly different from the microsphere whole-wall flow rates. The variability between the methods shown by the test-retest difference revealed only a minor lack of agreement. The bladder blood flow tended to decrease after the intravesical pressure had been increased to 20 cmH2O, but the difference was not statistically significant. Washout of locally injected 133Xe can be used for the evaluation of urinary bladder blood flow in humans and in longitudinal animal studies. The corrected-initial-slope method is recommended for the analysis of washout curves.