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Biomedical subjects

L R Burwell

Publications and source records attributed to L R Burwell.

22 records · Page 2Linked to original sources
PubMed1969

Inhibition of the effects of angiotensin II on adrenal steroid production by dietary sodium.

The pressor octapeptide, angiotensin II, can stimulate the production of aldosterone by the adrenal cortex. The present results show that in the dog a high-sodium diet can eliminate the steroidogenic action of angiotensin II, which is thus dissociated from the pressor action which remains. Angiotensin II was infused intravenously for 48 hours into conscious, undisturbed hypophysectomized dogs that were receiving each day either 60 or 200 mEq of dietary sodium. Blood pressure and secretion of aldosterone, corticosterone, and cortisol were measured (1) throughout the infusion in some dogs, and (2) at the end of the infusion in all dogs. In those dogs receiving 60 mEq of sodium, angiotensin II elevated the blood pressure and produced sustained increases of secretion of aldosterone, corticosterone, and cortisol. In those dogs receiving 200 mEq of sodium, angiotensin II, while retaining its pressor activity, had no effect on the production of aldosterone, corticosterone, or cortisol after 24 hours. Thus, if angiotensin II can produce hypertension clinically, there need not be secondary aldosteronism as well.

Adrenal Cortex Hormones↗
PubMed1968

Sites of action of sodium depletion on aldosterone biosynthesis in the dog.

Secretion of cortisol, corticosterone, and aldosterone was measured in vivo in normal and sodium-depleted hypophysectomized dogs. Biogenesis of steroids was then measured in vitro with outer slices of the adrenals of the same dogs. In some studies, metyrapone or puromycin was added. In vivo, sodium depletion stimulated the production of cortisol, corticosterone, and aldosterone. In vitro, tissues from sodium-depleted animals released more aldosterone, but less corticosterone than those from sodium-replete controls. The results are interpreted to indicate that (a) biosynthesis of aldosterone is regulated at at least two sites in the biosynthetic pathway. The final conversion, that of corticosterone to aldosterone, is stimulated by sodium depletion. This effect persists for at least 3 hr while slices from sodium-depleted dogs are incubated in vitro. Stimulation at this site is thus relatively stable in vitro; its activation by sodium depletion is not inhibited by puromycin in the dog. Stimulation at this site can explain, at least in part, the increased effectiveness of adrenocorticotropin (ACTH) on aldosterone biogenesis during sodium depletion.(b) the earlier site at which sodium depletion stimulates the secretion of aldosterone is "above" the position of desoxycorticosterone in the pathway; it is probably at the conversion of cholesterol to pregnenolone. Stimulation at this site is quickly lost during incubation of adrenal slices. It is thus relatively unstable in vitro; its activation by sodium depletion is inhibited by puromycin in the dog.

Adrenal Glands↗