Dissociation of Testosterone From Plasma Protein During Superfusion of Slices From Human Prostate

Giorgi, Eleonora P.; Moses, Theresa F.

doi:10.1677/joe.0.0650279

Cited by 24 publications

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“…Sex steroid-binding globulin is absent from dog plasma and the androgens are bound only to transcortin and albumin (Westphal, 1971). Testosterone concentration is low in canine prostate (Gloyna, Siiteri & Wilson, 1970), while it is high in plasma (Tremblay, Forest, Shalf, Martel, Kowarski & Migeon, 1972); some dissociation from plasma protein might also occur during the passage of blood through the capillaries (Giorgi & Moses, 1975). Thus, it is possible that very little testosterone is free in the tissue and that there is a positive concentration gradient from plasma to tissue.…”

Section: Resultsmentioning

confidence: 99%

Studies on Androgen Transport Into Canine Prostate in Vitro

Giorgi¹

1976

Journal of Endocrinology

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Slices from canine prostate were superfused with [17alpha-3H] testosterone and 5alpha-dihydro[1,2-3H]testosterone at 'physiological' concentrations; to some wuperfusions, either [3H]cyproterone or [3H]cyproterone acetate was also added. The following parameters were measured: 'uptake' of anti-androgen by the tissue, rate of entry of testosterone and 5alpha-dihydrotestosterone into the tissue, rate of efflux from the tissue of 5alpha-dihydrotestosterone and concentration of 'diffusible' 5alpha-dihydrotestosterone in the slices. The adsorption of steroids on to the surface of the slices and the bulk flow of tritiated water into the slices were also investigated. It was concluded that these two factors did not interfere with the measurement of entry and efflux of the androgens. Cyproterone and cyproterone acetate were not metabolized, but were concentrated in the slices to many times the level in the medium. With rate of supply of anti-androgens up to 43 pmol/min, their uptake increased together with the rate of entry of the two androgens and the rate of efflux of 5alpha-dihydrotestosterone. At a higher rate of supply of anti-androgens, their uptake and the rates of entry and efflux of the androgens decreased sharply. In most cases, the inward movement of 5alpha-dihydrotestosterone into the slices took place against a negative concentration gradient, while that of testosterone always occurred down a positive concentration gradient. These results confirmed the hypothesis already put forward that 'carriers' involved in the transport of androgens are present in the membrane of prostatic cells (Giorgi, Moses, Grant, Scott & Sinclair, 1974). Non-specific and specific intracellular binding, exhibiting greater affinity for 5alpha-dihydrotestosterone than for testosterone, was demonstrated in canine prostate by means of 'washing-out' experiments. On the basis of its affinity for androgens and the presence of inhibition by low concentrations of anti-androgen, intracellular binding seemed to be due to components distinct from the postulated membrane 'carriers'.

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Section: Resultsmentioning

confidence: 99%

Studies on Androgen Transport Into Canine Prostate in Vitro

Giorgi¹

1976

Journal of Endocrinology

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“…A new method, based on ultrafiltration, is described in this study. It is basically similar to the method employed for the assay of serum-free cortisol (Murray 1967) and for free, labelled testosterone in plasma (Giorgi & Moses 1975).…”

Section: Discussionmentioning

confidence: 99%

Testosterone concentrations in human seminal plasma and saliva and its correlation with non‐protein‐bound and total testosterone levels in serum

et al. 1983

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A sensitive, specific and precise non-chromatographic method for the radioimmunoassay of testosterone in human seminal plasma and saliva from adult and pubertal males is described, and the values compared to total and non-protein-bound testosterone levels in serum. There was a significant correlation between salivary and serum-free levels of testosterone (r = 0.75, P less than 0.001, n = 67) whilst the correlation of serum levels of total testosterone with free as well as with salivary testosterone levels was weaker (r = 0.63 and 0.64, respectively). The salivary and serum levels of free testosterone showed better correlation with the stage of puberty than did the serum levels of total testosterone. Further evidence for a correlation between salivary and serum levels of free testosterone was obtained following oral administration of testosterone undecanoate, as this treatment increased the mean concentration of serum total testosterone after 3 h by 82%, but increased salivary and serum levels of free testosterone by only 30% and 20%, respectively. The coefficient of correlation between serum levels of total testosterone and seminal plasma testosterone was 0.73 (P less than 0.001), whilst the correlation between levels of serum-free testosterone with both salivary and seminal plasma levels of testosterone was statistically non-significant. Our observations on salivary testosterone are in accordance with the diffusion of non-protein-bound steroids into peripheral tissues, and consequently into their secretions. This model, however, does not appear to be applicable to the sex accessory glands.

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A rapid procedure for measurement of the free testosterone fraction in human plasma using the centria radioimmunoassay centrifugal analyzer

Schwarz

Boyd

1981

Arch. Gynecol.

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Following the incubation of plasma with a tracer amount of tritiated testosterone, the reaction mixture is separated into a sex hormone-binding globulin bound and an unbound fraction of radioligand using DEAE-cellulose columns placed in the incubator-separator module of the Centria radioimmunoassay centrifugal analyzer. Neural Tris-buffer elutes unbound steroid from the matrix, while acidic Tris-buffer can remove the protein-bound fraction in a subsequent step. Complementary and thus qualitatively equal results are obtained when counting either eluate. Comparison of this technique with an ammonium sulfate precipitation method showed high correlation. Free testosterone indices as determined by the Centria modification in a number of prepuberal children, normal men and women, as well as pregnant and hirsute women similar to those previously reported.

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Dissociation of Testosterone From Plasma Protein During Superfusion of Slices From Human Prostate

Cited by 24 publications

References 0 publications

Studies on Androgen Transport Into Canine Prostate in Vitro

Studies on Androgen Transport Into Canine Prostate in Vitro

Testosterone concentrations in human seminal plasma and saliva and its correlation with non‐protein‐bound and total testosterone levels in serum

A rapid procedure for measurement of the free testosterone fraction in human plasma using the centria radioimmunoassay centrifugal analyzer

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