Zusammenfassung
Die Ergebnisse neuerer klinischer und experimenteller Untersuchungen haben die Brauchbarkeit der katheterlosen seitengetrennten Bestimmung der mJ-Hippuran-Clearance zur Funktionsbeurteilung akut gestauter Nieren in Frage gestellt. Bei den in herkömmlicher Weise durchgeführten Clearanceuntersuchungen besteht die Schwierigkeit, den während der Harnstauung produzierten Urin quantitativ zu bestimmen. An 6 Hunden wurden daher in simultaner Messung die renalen Extraktionen von P-Aminohippursäure und 131 J-Hippuran vor und nach akuter Harnstauung bei konstantem Plasmaspiegel der Prüfsubstanzen bestimmt. Die mit dieser sehr aufwendigen, von einer Urinsammlung jedoch unabhängigen Methode gewonnenen Ergebnisse zeigen, daß eine akute Harnabflußstauung zu einer Abnahme der renalen Ausscheidung sowohl der PAH als auch des 131 J-Hippuran führt. Die mit der katheterlosen Bestimmung der 131 J-Hip- puran-Clearance wiederholt gefundene “Zunahme” der renalen Leistung in unmittelbarem Anschluß an eine experimentell induzierte Harnabflußsperre kann demnach nicht durch ein unterschiedliches kinetisches Verhalten der PAH und des 131 J-Hippuran in der akut gestauten Niere erklärt werden.
Summary
The results of more recent clinical and experimental investigations have thrown doubt on the usefulness of determining the individual mI-hippurate clearance for evaluation of the function of acutely obstructed kidneys. There is a significant difference (5% level) between the kidney performance determined with external measurement on the one hand and with PAH and l25 I-hippurate clearance in the steady state on the other. With the steady state method, the restriction of function to be expected in consequence of urinary obstruction is demonstrated, whereas with simultaneous measurement with catheterless 131 I-hippurate clearance, an increase in function is detected. In the clearance studies carried out in the conventional way with PAH and l25 I-hippurate, it was difficult to determine quantitatively the urine produced during urinary obstruction. The renal extraction of p-aminohippuric acid and 131 I-hippurate was therefore determined in simultaneous measurement in six dogs before and after acute urinary obstruction with a constant plasma level of the test substances. The results obtained with this very elaborate method which is, however, independent of urine collection show that an acute urinary obstruction leads to a decrease of renal extraction both of PAH and of 131 I-hippurate. Since with conventional clearance, the measurement result is proportional to the amount of substance excreted with the urine, a restriction of function must also result with the steady state methods in determining the performance of acutely obstructed kidneys. The results of the extraction investigations hence confirm the results of the clearance studies mentioned. In addition, they show that the “increase” of renal performance immediately after an experimentally induced urinary obstruction repeatedly found with catheterless determination of 131 I-hippurate-clearance cannot be explained by a different kinetic behavior of PAH and 131 I-hippurate in the acutely obstructed kidney.
