strontium-radioisotopes and Ureteral-Obstruction

To evaluate the relative contribution of endogenous vasoactive compounds to maintenance of increased renal vascular resistance in neonatal obstructive nephropathy, cardiac output and renal blood flow were measured using radioactive microspheres in 25 +/- 3 day-old guinea pigs subjected to unilateral partial ureteral constriction within the first two days of life. Mass and renal blood flow of the obstructed kidney were significantly lower than those of the contralateral kidney. Following a control period, thromboxane synthesis was blocked by infusion of OKY-046, after which prostaglandin synthesis was inhibited by indomethacin. In a separate group of animals, angiotensin converting enzyme inhibitor, MK-422, was infused before or after administration of OKY-046. While neither OKY-046 nor indomethacin had a consistent effect on vascular resistance, infusion of MK-422 resulted in selective reduction of renal vascular resistance of the obstructed kidney compared to resistance in the intact kidney and other vascular beds. Removal of the contralateral kidney at the time of ureteral constriction in an additional group of animals resulted in hypertrophy and vasodilation of the obstructed kidney which was not altered by thromboxane or cyclooxygenase inhibition. We conclude that in the neonatal kidney subjected to ipsilateral chronic partial ureteral obstruction, vasoconstriction is mediated at least in part by angiotensin II, but not by thromboxane. Furthermore, vasodilation of the obstructed kidney resulting from contralateral nephrectomy is not dependent on prostaglandin synthesis. Renal vascular resistance of the kidney with prolonged partial ureteral constriction in early development thus appears to be inversely related to renal growth and is not significantly mediated by endogenous prostanoids.

Topics: Angiotensin II; Animals; Animals, Newborn; Cardiac Output; Enalapril; Enalaprilat; Female; Guinea Pigs; Indomethacin; Kidney; Male; Methacrylates; Microspheres; Prostaglandins; Renal Circulation; Strontium Radioisotopes; Thromboxanes; Time Factors; Ureteral Obstruction; Vascular Resistance

Intrarenal haemodynamics were investigated in the dog prior to and after relief of 24 hr bilateral ureteral ligation (BUL), by the radioactive microsphere technique. Prior to release of 24 hr BUL there was an about 50% reduction in total blood flow (RBR), with a nearly proprotional decrease in the perfusion of the four cortical layers. Following release of the obstruction, total renal and outer cortical (zones 1 and 2) blood flow remained diminished, while perfusion of the inner (juxtamedullary) layers (zones 3 and 4) increased as compared to its prerelease values and equalled controls. Glomerular filtration rate (GFR) amounted to about 27% of controls in the postrelease phase. A marked increase in absolute and fractional sodium water excretion was observed after release of 24 hr BUL, as contrasted to normal controls and dogs after 24 hr unilateral ureteral ligation (UUL). This state, designated as postopstructive diuresis, might be explained by redistribution of intrarenal blood flow towards the juxtamedullary zones, and by a powerful natriuretic substance accumulated during complete obstruction.

Topics: Animals; Cesium Radioisotopes; Diuresis; Dogs; Female; Glomerular Filtration Rate; Hemodynamics; Kidney; Kidney Cortex; Kidney Glomerulus; Ligation; Male; Microspheres; Regional Blood Flow; Strontium Radioisotopes; Ureteral Obstruction

Renal blood flow was measured in bilateral ureteral obstruction (BUO) and unilateral ureteral (UUO) obstruction. Renal blood flow of BUO and UUO rats before release of 24-hr obstruction was approximately 69 per cent and 77 per cent of control values, respectively. No redistribution of intrarenal blood flow was noted in UUO and BUO rats. Prerelease ureteral pressure of BUO rats (27.6 +/- 1.60 mm Hg) was significantly higher than that of UUO rats (14.4 +/- 1.30 mm Hg, P less than 0.001). Although the blood urea nitrogen of UUO rats with urine reinfusion was similar to that of BUO rats, the ureteral pressure was 14.8 +/- 1.93 mm Hg. Therefore, the higher ureteral pressure of BUO rats is not due to elevation of blood urea nitrogen. It is concluded that decreased renal blood flow during obstruction and high ureteral pressure may result in more severe tubular damage in BUO than in UUO. The decreased renal perfusion is probably due to changes in intrarenal vascular tone rather than due to intersitial pressure.

Topics: Animals; Blood Urea Nitrogen; Capillaries; Hemodynamics; Kidney; Kidney Cortex; Kidney Glomerulus; Kidney Tubules, Proximal; Male; Microspheres; Pressure; Rats; Regional Blood Flow; Strontium Radioisotopes; Ureter; Ureteral Obstruction; Urine; Vascular Resistance

Topics: Aminohippuric Acids; Animals; Blood Flow Velocity; Cesium Isotopes; Dogs; Female; Filtration; Glomerular Filtration Rate; Kidney; Kidney Concentrating Ability; Kidney Cortex; Kidney Medulla; Microspheres; Natriuresis; Potassium; Pressure; Radioisotopes; Regional Blood Flow; Strontium Radioisotopes; Time Factors; Urea; Ureteral Obstruction; Water

Topics: Animals; Body Weight; Diuresis; Glomerular Filtration Rate; Hematocrit; Hemodynamics; Ischemia; Kidney; Kidney Cortex; Male; Microspheres; Rats; Regional Blood Flow; Strontium Radioisotopes; Time Factors; Ureteral Obstruction; Urine

Topics: Adult; Bone Neoplasms; Female; Humans; Hydronephrosis; Middle Aged; Neoplasm Metastasis; Pelvic Neoplasms; Radionuclide Imaging; Strontium Isotopes; Strontium Radioisotopes; Ureteral Obstruction