Epinephrine in rat hypophysial portal blood is derived mainly from the adrenal medulla

Neuroendocrinology
G PesceC Oliver

Abstract

This study was performed to determine if epinephrine (EPI) present in hypophysial portal blood has a peripheral or a central origin. Pituitary stalk and femoral arterial EPI plasma levels were simultaneously measured in rats anesthetized with thiopental or urethane. EPI was measured by two different methods: radioenzymatic assay or HPLC followed by electrochemical detection. In thiopental-anesthetized rats, levels were higher in hypophysial portal than in femoral arterial plasma with both methods. In urethane-anesthetized rats, no difference in EPI concentrations was found between peripheral and portal plasma. A rapid blood volume depletion (15 ml/kg in 3 min) evoked a marked elevation of pituitary stalk and arterial EPI plasma concentration while norepinephrine (NE) and dopamine (DA) levels were unaffected. Under both types of anesthesia, the increase of EPI levels was higher in peripheral than in portal plasma. After removal of the adrenal glands, EPI was undetectable or barely detectable in pituitary stalk and arterial plasma. The hemorrhage-induced stimulation of EPI secretion was blunted in portal and peripheral plasma of adrenalectomized rats. These findings indicate that: (1) hypophysial portal EPI plasma concentration i...Continue Reading

Citations

Apr 1, 1993·Baillière's Clinical Endocrinology and Metabolism·S al-Damluji
Jun 12, 2002·Endocrinology and Metabolism Clinics of North America·Jacobo Wortsman
Mar 1, 2001·Stress : the International Journal on the Biology of Stress·G B MakaraS L Lightman

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