DETERMINATION OF EXTRACTION FRACTION BY A DOUBLE-TRACER METHOD

  • 1 January 1977
    • journal article
    • research article
    • Vol. 18  (3) , 226-230
Abstract
A relatively simple dual-tracer method for measuring renal extraction fraction was compared with the direct method. [Adult mongrel dogs were studied.] In the dual-tracer method an extracted and nonextracted tracer were mixed together and administered into the arterial circuit and samples of venous blood were obtained. The ratio of recovered to injected tracer then determined the extraction fraction. The direct method tracer was administered directly into the renal artery and the total venous effluent was collected. Extraction fraction was then calculated as arteriovenous difference divided by the quantity injected. The extraction fractions for 201Tl and 203Hg-chlormerodrin were determined. The extraction fraction for 201Tl averaged 81 .+-. 5% by the direct method and 81 .+-. 6% by the dual-tracer technique (r [correlation coefficient] = 0.94). The extraction fraction for 203Hg-chlormerodrin changed as a function of the renal blood flow. At normal flow the extraction fraction averaged 48% by the direct method and 45% by the dual-tracer technique. At reduced flow, in contrast, it averaged 78% by the direct method and 71% by the dual-tracer technique.

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