Osmosensitivity of the hepatic portal vein area and vasopressin release in rats.

1. The role of intraperitoneal osmoreceptors in hypothalamo-neurohypophyseal control was studied in urethane- or nembutal-anaesthetized rats. Plasma samples were taken for radioimmunoassay of arginine vasopressin, and the electrical activity of single supraoptic endocrine neurones and of the hypothalamo-neurohypophyseal tract were monitored during superfusion of the hepatic portal vein with hypo-, iso- and hypertonic solutions. 2. Plasma arginine vasopressin increased within 1 min following superfusion with 0.3-0.9 osmolal NaCl solutions in a dose-related manner from basal levels of 30 pg/ml, ...

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