The Pressure-Volume Relationship of the Pig Renal Pelvis

Abstract

In five pigs weighing approximately 85 kg. the pelvic pressure-volume relationship was investigated. Through a catheter introduced into the renal pelvis from the ureter with ligation at the ureteropelvic junction, a continuous filling of one ml./minute was established. After drainage of the pelvis filling was begun showing an exponential relationship between pressure and volume. Fillings in all of the units confined the equation y = a + bx + cx2. Emptying showed unanimously clockwise hysteresis although 1/3 of the fillings revealed active contractile forces with an inverted S-shaped emptying curve. The normal multicalyceal renal pelvis in pigs of the same size showed a wide range of pressure-volume relationships both between individuals and between the two investigations. This wide range might be of importance in the development of dilatations due to obstruction.

Obstructive Nephropathy in the pig Aspects of renal hemodynamics and hormonal changes during acute unilateral ureteral obstruction

“…Taking into account the observations by Moody et al (21), that the initial phase of obstruction also contain a postglomerular vasoconstric-tor component, administration of an ACE inhibitor theoretically could be associated with a relative reduction of postglomerular resistance, fkther reducing filtration pressure. And it must be recognized that the pelvic smooth muscle wall exhibits a large compliance (116,117), where minor change in urine output caused by hemodynamic changes is not detectable.…”