Abstract
Milk-ejection responses to whole posterior pituitary extracts, to tap stimuli and the effects of adrenaline on these responses were studied in anaesthetized lactating rabbits.
Intravenous injection of the whole posterior pituitary extracts caused the ejection response after latent period of about 10-30 sec. Total duration of the response was 35-300 sec.
Latency, duration and magnitude of the responses varied markedly not only from animal to animal but for each animal.
One to 2 sec. after the application of tap stimuli, ejection responses occurred and lasted for about 30 sec. Type of these responses was quite alike to that evoked by 10-25mU. of whole posterior pituitary extracts.
Five μg of adrenaline suppressed the ejection response to whole posterior pituitary extracts, when administered before the injection of oxytocic substances.
But the responses to tap stimuli were not affected by adrenaline administration.
These observations confirmed the findings obtained by Cross (1953, 1954, 1955), and Cross and Harris (1953).
