INTERSTITIAL ALBUMIN MASS AND TRANS-CAPILLARY EXTRAVASATION RATE OF ALBUMIN IN DMBA-INDUCED RAT MAMMARY-TUMORS

  • 1 January 1983
    • journal article
    • research article
    • Vol. 43  (6) , 503-512
Abstract
Transcapillary extravazation rate for radioiodinated human serum albumin (I-HSA) from plasma to interstitial fluid, interstitial albumin mass and interstitial albumin concentration were determined in dimethylbenz[a]anthracene (DMBA)-induced mammary tumors in rats. The plasma radioactivity of tracer was kept constant in awake, freely moving rats by a continuous infusion of I-HSA from 1-72 h after an initial priming dose. Capillary leakiness for I-HSA was calculated as the plasma equivalent volume of I-HSA located extravascularly after 1 h infusion divided by the blood volume in the tissue, i.e., as the fractional extravasation rate (FER). The experiments showed that FER was highest in tumors while intestine and skin had FER of about 70% and 25% that of tumor, respectively. Heart and skeletal muscle had similar FER about 1/8 that of tumor. Interstitial albumin concentration in tumor averaged 42% of plasma albumin concentration in tumor. Intestine, heart and skeletal muscle had interstitial albumin concentrations between 34 and 37% of plasma albumin concentration while skin had an albumin concentration averaging 20% that of plasma. Lymph flow was calculated as the product of the fractional turnover rate constant for interstitial albumin and interstitial volume (extravascular 51Cr-EDTA volume), and averaged 36.7 .cntdot. 10-3 mg/g .cntdot. h in tumor while intestine and heart had lymph flows of 19.1 .cntdot. 10-3 and 14.1 .cntdot. 10-3 ml/g .cntdot. h, respectively. In muscle and skin lymph flow was 2.4 .cntdot. 10-3 and 18.3 .cntdot. 10-3 ml/g .cntdot. h, respectively. The high interstitial fluid pressure previously observed in these tumors may contribute in maintaining interstitial volume in a steady-state by opposing fluid filtration into the interstitium and maintaining a lymph flow high enough to remove excess fluid and protein from the interstitium.

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