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Renal 131I-hippurate clearance overestimates true renal blood flow in the instrumented conscious dog.
- Source :
-
The American journal of physiology [Am J Physiol] 1996 Aug; Vol. 271 (2 Pt 2), pp. F269-74. - Publication Year :
- 1996
-
Abstract
- We evaluated renal 131I-hippurate clearance (ERPFhip) as a measure of renal blood flow (RBF) in chronically instrumented conscious dogs. When adjusted for renal hippurate extraction (Ehip, 0.77 +/- 0.01) and hematocrit (Hct, 39.7 +/- 1%), calculated RBFhip (656 +/- 37 ml/min) markedly exceeded renal blood flow measured with renal artery blood flow probes (RBFprobe, 433 +/- 27 ml/min). The discrepancy could not be explained by flow probe calibration, because in vivo comparison of flow probe values with renal venous outflow showed only a slight underestimation of renal blood flow (slope 0.93, 95% confidence interval 0.89-0.97). Redistribution of hippurate from erythrocytes into renal venous plasma during or shortly after blood sampling led to an underestimation of Ehip by 4 +/- 1% and thus could only explain a small part of the difference. Extrarenal hippurate clearance was excluded, because the amount of 131I-hippurate cleared from plasma equaled that appearing in the urine (303 +/- 17 and 307 +/- 17 ml/min). Applying these corrections, we found that RBFhip still exceeded RBFprobe by 37 +/- 3%. These data indicate that renal blood flow measured by the hippurate clearance technique markedly overestimates true renal blood flow. Because other errors were excluded, a combination of sampling of nonrenal blood and intrarenal hippurate extraction from erythrocytes might play a role.
Details
- Language :
- English
- ISSN :
- 0002-9513
- Volume :
- 271
- Issue :
- 2 Pt 2
- Database :
- MEDLINE
- Journal :
- The American journal of physiology
- Publication Type :
- Academic Journal
- Accession number :
- 8770157
- Full Text :
- https://doi.org/10.1152/ajprenal.1996.271.2.F269