Glucocorticoids potentiate central actions of angiotensin to increase arterial pressure.
Experiments were performed to determine if glucocorticoids potentiate central hypertensive actions of ANG II. Male Sprague-Dawley rats were treated for 3 days to 3 wk with corticosterone (Cort). Experiments were performed in conscious rats that had previously been instrumented with arterial and venous catheters and an intracerebroventricular guide cannula in a lateral ventricle. Baseline arterial pressure (AP) was greater in Cort-treated rats than in control rats (119 +/- 2 vs. 107 +/- 1 mmHg, P < 0.01). Microinjection of ANG II intracerebroventricularly produced a significantly larger increase in AP in Cort-treated rats than in control rats. For example, at 30 ng ANG II, AP increased by 23 +/- 1 and 16 +/- 2 mmHg in Cort-treated and control rats, respectively (P < 0.01). Microinjection of an angiotensin type 1 receptor antagonist significantly decreased AP (-6 +/- 2 mmHg) and heart rate (-26 +/- 7 beats/min) in Cort-treated but not control rats. Increases in AP produced by intravenous administration of ANG II were not different between control and Cort-treated rats. Intravenous injections of ANG II antagonist had no significant effects on mean AP or heart rate in control or Cort-treated rats. Therefore, a sustained increase in plasma Cort augments the central pressor effects of ANG II without altering the pressor response to peripheral administration of the hormone.
Scheuer
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DA
Department of Pharmacology, The University of Missouri-Kansas City, Kansas City, Missouri 64108, USA. scheuerd@umkc.edu
Bechtold
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AG
D000804:Angiotensin II / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D057911:Angiotensin Receptor Antagonists; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects*; D001921:Brain / Q000187:drug effects*; D003345:Corticosterone / Q000097:blood / Q000494:pharmacology*; D004357:Drug Synergism; D007093:Imidazoles / Q000494:pharmacology; D007275:Injections, Intravenous; D007276:Injections, Intraventricular; D019808:Losartan / Q000494:pharmacology; D008297:Male; D008845:Microinjections; D051381:Rats; D017207:Rats, Sprague-Dawley; D044140:Receptor, Angiotensin, Type 1; D044139:Receptor, Angiotensin, Type 2; D012016:Reference Values; D013777:Tetrazoles / Q000494:pharmacology
D057911:Angiotensin Receptor Antagonists; D007093:Imidazoles; D044140:Receptor, Angiotensin, Type 1; D044139:Receptor, Angiotensin, Type 2; D013777:Tetrazoles; D000804:Angiotensin II; C070967:L 158809; D019808:Losartan; D003345:Corticosterone