TeBG- and CBG-bound steroid hormones in rabbits are available for influx into uterus in vivo

Journal Article · Fri Jan 01 04:00:00 EST 1988 · American Journal of Physiology; (USA)

OSTI ID:6945403

Chaudhuri, G; Steingold, K A; Pardridge, W M; Judd, H L ^[1]

---

1. Univ. of California, Los Angeles (USA)

The metabolic clearance rate (MCR) of gonadal or adrenal steroid hormones in rabbits often does not bear the expected inverse relationship with hormone binding to testosterone-binding globulin (TeBG) or corticosteroid-binding globulin (CBG). This suggests TeBG or CBG may not impede steroid hormone delivery to tissues. The effects of rabbit plasma proteins on the influxes of {sup 3}H-labeled steroids from the circulation into the rabbit uterus were measured in vivo using a tissue sampling single-injection technique. In the absence of plasma proteins, estradiol (E{sub 2}) and testosterone (T) were freely diffusible through the uterine microvasculature (i.e., extraction >80%). The extractions of dihydrostestosterone (DHT) and corticosterone (B) ranged from 60 to 72%, while that of cortisol (F) was reduced at 40%. Rabbit serum exerted no inhibition of the influxes of the steroids tested. The influxes of T and B greatly exceeded the rates that would be expected if only the free and albumin-bound fractions estimated in vitro were diffusible in vivo. However, the extraction of ({sup 3}H)corticosteroid-binding globulin or bovine ({sup 3}H)albumin were low, consistent with little, if any, extravascular uptake of the plasma proteins. The results indicate both albumin-bound and globulin-bound steroid hormone are available for transport into the uterus in the rabbit in vivo without significant exodus of the plasma protein, per se.

• OSTI ID: 6945403
• Journal Information: American Journal of Physiology; (USA), Journal Name: American Journal of Physiology; (USA) Vol. 254:1; ISSN 0002-9513; ISSN AJPHA
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ADRENAL HORMONES
ALBUMINS
ANDROGENS
ANDROSTANES
ANIMALS
BLOOD-PLASMA CLEARANCE
BODY
CLEARANCE
CORTICOSTEROIDS
FEMALE GENITALS
GLOBULINS
HORMONES
HYDROGEN COMPOUNDS
HYDROXY COMPOUNDS
KETONES
MAMMALS
ORGANIC COMPOUNDS
ORGANS
PREGNANES
PROTEINS
RABBITS
STEROID HORMONES
STEROIDS
TESTOSTERONE
TRITIUM COMPOUNDS
UPTAKE
UTERUS
VERTEBRATES