Aldosterone induces endothelial dysfunction in resistance arteries from normotensive and hypertensive rats by increasing thromboxane A2 and prostacyclin.
OBJECTIVE
The present study was designed to assess whether cyclooxygenase-2 (COX-2) activation is involved in the effects of chronic aldosterone treatment on endothelial function of mesenteric resistance arteries (MRA) from Wistar-Kyoto (WKY) and spontaneously hypertensive rats (SHR).


METHODS
Relaxation to acetylcholine was measured in MRA from both untreated and aldosterone-treated strains. Vasomotor responses to prostacyclin and U46619 were also analysed. Release of 6-oxo-prostaglandin (PG)F1alpha and thromboxane B2 (TxB2) was determined by enzyme immunoassay. COX-2 protein expression was measured by western blot.


RESULTS
Aldosterone reduced acetylcholine relaxation in MRA from both strains. In MRA from both aldosterone-treated strains the COX-1/2 or COX-2 inhibitor (indomethacin and NS-398, respectively), TxA2 synthesis inhibitor (furegrelate), prostacyclin synthesis inhibitor (tranylcypromine) or TxA2/ PGH2 receptor antagonist (SQ 29 548), but not COX-1 inhibitor SC-560, increased acetylcholine relaxation. In untreated rats this response was increased only in SHR. Prostacyclin elicited a biphasic vasomotor response: lower concentrations elicited relaxation, whereas higher concentrations elicited contraction that was reduced by SQ 29 548. Aldosterone increased the acetylcholine-stimulated production of 6-oxo-PGF(1alpha) and TxB2 in MRA from both strains. COX-2 expression was higher in both strains of rats treated with aldosterone.


CONCLUSIONS
Chronic treatment with aldosterone impaired endothelial function in MRA under normotensive and hypertensive conditions by increasing COX-2-derived prostacyclin and thromboxane A2. As endothelial dysfunction participates in the pathogenesis of many cardiovascular disorders we hypothesize that anti-inflammatory drugs, specifically COX-2 inhibitors, could ameliorate vascular damage in patients with elevated aldosterone production.
Xavier
F E
FE
Departamento de Fisiologia e Farmacologia, Centro de Ciências Biológicas, Universidade Federal de Pernambuco, Recife, Brazil.
Aras-López
R
R
Arroyo-Villa
I
I
del Campo
L
L
Salaices
M
M
Rossoni
L V
LV
Ferrer
M
M
Balfagón
G
G
D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid / Q000494:pharmacology; D000450:Aldosterone / Q000494:pharmacology*; D000818:Animals; D015153:Blotting, Western; D051545:Cyclooxygenase 1 / Q000378:metabolism; D051546:Cyclooxygenase 2 / Q000378:metabolism; D004730:Endothelium, Vascular / Q000187:drug effects*; D011464:Epoprostenol / Q000378:metabolism*; D066298:In Vitro Techniques; D008297:Male; D008638:Mesenteric Arteries / Q000473:pathology; D009126:Muscle Relaxation / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000187:drug effects; D009638:Norepinephrine / Q000494:pharmacology; D011189:Potassium Chloride / Q000494:pharmacology; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D013928:Thromboxane A2 / Q000378:metabolism*; D014652:Vascular Diseases / Q000139:chemically induced* / Q000473:pathology; D014655:Vascular Resistance / Q000187:drug effects; D014662:Vasoconstrictor Agents / Q000494:pharmacology
D014662:Vasoconstrictor Agents; D000450:Aldosterone; D013928:Thromboxane A2; D011189:Potassium Chloride; D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; D011464:Epoprostenol; D051545:Cyclooxygenase 1; D051546:Cyclooxygenase 2; D009638:Norepinephrine