HIGH CORTICOSTEROID LEVELS IN PLASMA OF ADULT AND FOETAL WEDDELL SEALS (LEPTONYCHOTES WEDDELLI)
ABSTRACT Pregnant and non-pregnant Weddell seals and foetuses were found to have very high plasma concentrations of corticosteroids (1–7 μmol/l) that were unaffected by stress. Cortisol comprised most of the corticosteroid in the adult but only 50 % of that in the foetus. The affinity constant (4.30–5.53 × 107 l/mol) and specificity of CBG and the MCR (4.5 l/d/kg lean body mass) in adult seals were similar to those of Man. The binding capacity of CBG (1.48–1.86 μmol/l) which is approximately three times that of Man contributed to the high plasma corticosteroid concentrations but the main factor was the cortisol turnover rate of 3670 μmol/d (1.3 g/d) which is the highest value reported in any species.