Des-Asp-1-angiotensin II. possible role in mediating the renin--angiotensin response in the rat.
Angiotensin II and its heptapeptide fragment, Des-Asp-1-angiotensin II, produced a striking increase in aldosterone secretion in rats pretreated with dexamethasone and morphine to reduce ACTH release. 1-Sar-8-Ala-angiotensin II (10 mug/kg min-1) given simultaneously with angiotensin II (1 mug/min) blocked the aldosterone response to angiotensin II in rats pretreated to reduce ACTH release. In contrast, 1-Sar-8-Ala-angiotensin II at the same dose failed to block the steroid response to Des-Asp-1-angiotensin II (1 mug/min) but a larger dose of 50 mug/kg min-1 of the angiotensin II antagonist blocked completely both the aldosterone and the corticosterone responses to 1 mug/min of Des-Asp-1-angiotensin II. From these data it is suggested that the heptapeptide has a higher affinity for zona glomerulosa receptors than the octapeptide and that Des-Asp-1-angiotensin II mediates, at least in part, the steroidogenic response to the renin-angiotensin system in the rat. The pressor response to Des-Asp-1-angiotensin II was approximately 50% of that produced by the octapeptide in the rat, and 1-Sar-8-Ala-angiotensin II was as effective in partially blocking the pressor response to the octapeptide as in inhibiting the heptapeptide. The present observations indicate a dissociation of adrenal cortex and peripheral arteriolar receptors in their affinity for angiotensin.
D000450:Aldosterone / Q000378:metabolism*; D000804:Angiotensin II / Q000031:analogs & derivatives* / Q000494:pharmacology; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects*; D003345:Corticosterone / Q000378:metabolism*; D003907:Dexamethasone / Q000494:pharmacology; D008297:Male; D009020:Morphine / Q000494:pharmacology; D051381:Rats; D012504:Saralasin / Q000494:pharmacology
D000804:Angiotensin II; D000450:Aldosterone; D009020:Morphine; D003907:Dexamethasone; D012504:Saralasin; D003345:Corticosterone