Mean Plasma Concentration, Metabolic Clearance and Basal Plasma Production Rates of Testosterone in Normal Young Men and Women Using a Constant Infusion Procedure: Effect of Time of Day and Plasma Concentration on the Metabolic Clearance Rate of Testosterone

Al, Southren; Gg, Gordon; Tochimoto, Satoru; Pinzon, Guillermo; Dr, Lane; Stypulkowski, Walter

doi:10.1210/jcem-27-5-686

Cited by 102 publications

(48 citation statements)

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“…For these two steroids, blood production rates, contribution of other precursors to blood production rates, and their metabolic clearance A portion of this work was presented at the International Congress on Hormonal Steroids, Milan, 1966. Received for publication 15 April 1969. rates are well documented (2,5,7,8,10). It has also been clearly demonstrated (5) that, in the normal female, 60% of the circulating testosterone is derived from androstenedione by peripheral conversion.…”

Section: Introductionmentioning

confidence: 92%

“…In recent years, many problems related to the secretion and metabolism of androgens, principally testosterone (T) and androstenedione (A) have been studied and partly elucidated (1)(2)(3)(4)(5)(6)(7)(8)(9). For these two steroids, blood production rates, contribution of other precursors to blood production rates, and their metabolic clearance A portion of this work was presented at the International Congress on Hormonal Steroids, Milan, 1966. Received for publication 15 April 1969. rates are well documented (2,5,7,8,10).…”

Section: Introductionmentioning

confidence: 99%

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Sites of in vivo extraction and interconversion of testosterone and androstenedione in dogs

Chapdelaine¹

1969

J. Clin. Invest.

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A B S T R A C T The interconversion and extraction of testosterone and androstenedione across and within different tissues or areas have been studied by the constant infusion technique. The results were calculated using the 8H/"C ratios and radioactive concentrations of testosterone and androstenedione obtained from afferent and efferent blood and tissues at equilibrium. In each tissue studied, the interconversion between testosterone and androstenedione inside the tissue was significantly higher than the corresponding interconversion across the tissue. The pulmonary contribution to the total interconversion between testosterone and androstenedione was far more important than that of any of the other tissues studied. The hepatic metabolic clearance rates of testosterone and androstenedione were not different from their metabolic clearance rates in the mesenteric area. The extraction of each of these compounds, although not negligible, was lower in the kidney and the femoral bed compared with the extraction in the liver and the mesenteric area. Finally, with the possible exception of the liver, testosterone and androstenedione were more completely metabolized when they originated from the cells than from afferent blood.The evaluation of these different tissue transfer constants provides more precise information concerning the relative importance of different sites in the metabolism of these interconverting hormones.

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Section: Introductionmentioning

confidence: 92%

Section: Introductionmentioning

confidence: 99%

Sites of in vivo extraction and interconversion of testosterone and androstenedione in dogs

Chapdelaine¹

1969

J. Clin. Invest.

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“…Guerra-García et al (1969) also noted similar results in urinary testosterone measurements in response to hCG challenges in urban Bolivian men living at sea level and individuals living at high altitude, although the researchers did not measure caloric intake. Furthermore, changes in urinary testosterone levels may not reflect alterations in circulating hormone levels, since production and clearance rates can vary independently (Cadoux-Hudson et al, 1985;Meikle et al, 1987;Southren et al, 1967). Compromised Leydig-cell sensitivity is also suggested by gonadotropin and salivary testosterone profiles in Ache men of Paraguay.…”

Section: Caloric Deficienciesmentioning

confidence: 99%

Reproductive ecology and life history of the human male

Bribiescas

2001

Am. J. Phys. Anthropol.

211

117

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Until recently, the reproductive ecology of human males has not been extensively investigated, primarily as a result of the need for a theoretical framework based on the reproductive constraints and energetics of mammalian males. More specifically, male reproductive ecology has necessitated an integrative interpretation of clinical and anthropological data based on the premise that the evolution of human male life histories has involved selection for physiological mechanisms aimed at optimizing trade-offs between survivorship and reproductive effort. This paper attempts to address this gap in our understanding by presenting the current state of male reproductive ecology, including physiologic data from clinical and anthropological investigations as well as recent theoretical developments. Recent investigations outlining population variation in reproductive endocrine function are discussed within the context of potential sources of variation, including energetic expediture, caloric intake, and developmental canalization during adolescence. Additional summaries of male senescence and behavior are presented to provide a complete overview of male life history. Implications of recent anthropological data on contemporary health issues such as prostate cancer and the development of a male contraceptive are also discussed. Finally, several theories are presented that may contribute to our understanding of the evolution of male life histories and reproductive ecology, including theoretical suggestions involving the role of competition, mate choosiness, and potential constraints on male insemination ability, as well as a theory suggesting that male reproductive ecology may be best understood by analyzing energetic allocation decisions between differing somatic tissues that may be indicative of the competing needs for optimizing survivorship and reproductive effort. Directions for future research are finally considered.

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“…Southern et al (22) MCRT and PBs in normal and hirsute females. They interpreted this correlation as being consistent with a depression of a testosterone-binding protein by increased testosterone production.…”

Section: Conversion Ratios and [P] Values The Conversionmentioning

confidence: 99%

Metabolism of testosterone and androstenedione in normal and ovariectomized women

Abraham¹,

Lobotsky²,

Lloyd³

1969

J. Clin. Invest.

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A B S T R A C T Metabolic clearance rates of testosterone (MCRT) and androstenedione (MCRA) were determined twice during the same cycle in six normal women, using a constant infusion of testosterone-2H and androstenedione-"C. Nonlabeled steroids served as internal standards. Plasma concentrations of testosterone (iT) and androstenedione (iA) were measured, and the blood production of testosterone (PBT) and of androstenedione (PBA) were calculated. The interconversions of these two steroids were also estimated. Six ovariectomized women were studied in the same manner. For testosterone, the mean i in the normal women was not significantly different from that in the ovariectomized subjects, whereas the MCRT and PET were significantly lower in the ovariectomized subjects. For androstenedione, the mean MCRA values of the two groups of subjects were not different, whereas the iA and PBA in the normal women were about double those in the ovariectomized subjects. In comparing the follicular and luteal phases of the menstrual cycle in four of six subjects there was no difference in iT, MCRT, or PBT, whereas iA, MCRA, and PBA were increased in the luteal phase. In one ovariectomized woman infused with testosterone and androstenedione at physiologic levels, MCRT doubled but MCRA remained the same. After six wk on estrogen, the same subject did not show any change in MCRT after infusion of testosterone. It is suggested that MCRT depends on PBT and on plasma binding of testosterone which is partly estrogen dependent.

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Mean Plasma Concentration, Metabolic Clearance and Basal Plasma Production Rates of Testosterone in Normal Young Men and Women Using a Constant Infusion Procedure: Effect of Time of Day and Plasma Concentration on the Metabolic Clearance Rate of Testosterone

Cited by 102 publications

References 0 publications

Sites of in vivo extraction and interconversion of testosterone and androstenedione in dogs

Sites of in vivo extraction and interconversion of testosterone and androstenedione in dogs

Reproductive ecology and life history of the human male

Metabolism of testosterone and androstenedione in normal and ovariectomized women

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