TY - JOUR

T1 - Whole-body microvascular permeability of small molecules in man: clinical aspects, basic concepts and limitations of the single injection technique

AU - Henriksen, Jens Henrik Sahl

N1 - Keywords: Adult; Aged; Capillary Permeability; Chromium Radioisotopes; Edetic Acid; Female; Glomerular Filtration Rate; Humans; Male; Microcirculation; Middle Aged; Molecular Weight; Plasma Volume; Serum Albumin, Radio-Iodinated; Sodium Radioisotopes

PY - 1985

Y1 - 1985

N2 - In order to estimate whole-body permeability-surface area (PS) product, the initial slope of the plasma disappearance curve was determined after simultaneous i.v. injection of 24Na+ (mol.wt 24) and 51Cr-EDTA (mol.wt 342). Twelve subjects were studied. Plasma volume (PV) was measured by the indicator dilution method, and the mean transit time of tracer in plasma was calculated as the reciprocal value of the initial fractional disappearance (initial slope). Estimated whole-body PS product (= PV/t) of 24Na+ (median 2.72, range 1.51-3.80 ml/min . 100 g body weight) was significantly higher than that of 51Cr-EDTA (median 2.16, range 1.59-2.84 ml/min . 100 g, p less than 0.005). The PS24Na:PS51Cr-EDTA ratio was median 1.26 (range 0.91-1.44), and this value is significantly lower than the ratio between the free aqueous diffusion coefficients (D24Na:D51Cr-EDTA = 2.54, p less than 0.005) but also significantly above unity p less than 0.005). The ratio between PS51Cr-EDTA and earlier estimates of whole-body PS product of polyfructosan (mol.wt 3000) was close to the ratio of their free diffusion coefficients. The results indicate that whole-body PS product may be estimated from the initial slope of the plasma disappearance curve of a tracer, but mixing problems and flow-limited transport, as indicated by a PS ratio below that of the free diffusion coefficients, may be difficult to overcome, especially when using tracers of a low molecular weight.

AB - In order to estimate whole-body permeability-surface area (PS) product, the initial slope of the plasma disappearance curve was determined after simultaneous i.v. injection of 24Na+ (mol.wt 24) and 51Cr-EDTA (mol.wt 342). Twelve subjects were studied. Plasma volume (PV) was measured by the indicator dilution method, and the mean transit time of tracer in plasma was calculated as the reciprocal value of the initial fractional disappearance (initial slope). Estimated whole-body PS product (= PV/t) of 24Na+ (median 2.72, range 1.51-3.80 ml/min . 100 g body weight) was significantly higher than that of 51Cr-EDTA (median 2.16, range 1.59-2.84 ml/min . 100 g, p less than 0.005). The PS24Na:PS51Cr-EDTA ratio was median 1.26 (range 0.91-1.44), and this value is significantly lower than the ratio between the free aqueous diffusion coefficients (D24Na:D51Cr-EDTA = 2.54, p less than 0.005) but also significantly above unity p less than 0.005). The ratio between PS51Cr-EDTA and earlier estimates of whole-body PS product of polyfructosan (mol.wt 3000) was close to the ratio of their free diffusion coefficients. The results indicate that whole-body PS product may be estimated from the initial slope of the plasma disappearance curve of a tracer, but mixing problems and flow-limited transport, as indicated by a PS ratio below that of the free diffusion coefficients, may be difficult to overcome, especially when using tracers of a low molecular weight.

M3 - Journal article

C2 - 3934741

VL - 45

SP - 509

EP - 513

JO - Scandinavian Journal of Clinical & Laboratory Investigation

JF - Scandinavian Journal of Clinical & Laboratory Investigation

SN - 0036-5513

IS - 6

ER -