Foetal and maternal plasma adrenaline and noradrenaline concentrations in the late pregnant rat: effects of intra-uterine isotonic saline or uterine handling.

The catecholamines adrenaline (A) and noradrenaline (NA) were determined in plasma samples of late pregnant rats and rat foetuses using a radioenzymatic procedure. In maternal plasma of control rats, values of A were stable during the last three days of gestation (between 5.64 and 6.90 ng/ml) whereas NA values increased just before parturition (+ 70%) and on day 23 post-coitum NA was the main plasma catecholamine. In foetal plasma of control rats, values of A and NA were constant during the last three days of gestation and A was always higher than NA. For both catecholamines, values in foetal plasma were lower than in maternal plasma. Blood of rats injected with isotonic saline into the uterus on day 21 of gestation contained 24 h and 48 h later about 2-3 times more A, and no more NA, than blood of control rats. In foetal plasma the levels of both catecholamines especially of NA were greatly increased after the handling of the uterus or the intra-uterine isotonic saline injection. Both treatments had the same prolonged effect upon A and NA values in foetal plasma. There is no increase of A and NA in maternal and foetal plasma after sham-operation. Although the values of plasma A and NA were high in control rats because of blood sampling was carried out under stressful conditions, these results showed that handling of the uterus or injection of intrauterine isotonic saline was a severe aggression for the mother and foetus.