Renal and systemic effects of chronic blockade of ET(A) or ET(B) receptors in normal rats and animals with experimental heart failure.
Endothelin-1 (ET-1) is involved in the pathogenesis of cardiac and renal hemodynamic changes and impaired excretory function in congestive heart failure. It has previously been demonstrated that acute administration of ABT-627 (endothelin-A blocker) abolished systemic and renal vasoconstriction in controls and rats with congestive heart failure induced by a surgically created aortocaval fistula (Abassi et al. Clin Sci (Lond) 2002;103:S245-S248). In contrast, acute endothelin-B blockade by A-192621 exaggerated the ET-1 induced systemic and renal vasoconstriction. The present study examined the renal and systemic effects of chronically administered ABT-627 (24 mg/kg per day) or A-192621 (72 mg/kg per day) for 7 days via osmotic minipumps inserted intraperitoneally on the day of operation of sham controls and rats with congestive heart failure. Tailcuff measurements revealed that ABT- 627 significantly decreased mean arterial pressure from 108 +/- 2 mmHg to 87 +/- 2 mmHg (P < 0.05), whereas A-192621 significantly increased mean arterial pressure from 110 +/- 3 mmHg to 122 +/- 3 mmHg (P < 0.05) in controls. Despite the hypotensive effect of ABT-627, daily sodium excretion dramatically increased, but to a lesser extent in A-192621-treated controls. Furthermore, chronic administration of ABT-627 to controls attenuated the systemic and renal vasoconstriction induced by ET-1 (1 nmol/kg intravenous), whereas A-192621 augmented these effects. Similarly, chronic treatment with ABT-627 totally abolished the systemic and renal vasoconstriction caused by injected ET-1 in rats with congestive heart failure, whereas A192621 potentiated these effects. Chronic treatment of animals with congestive heart failure with ABT-627 did not influence daily sodium excretion, whereas treatment with A192621 significantly improved daily sodium excretion. Interestingly, treatment with either ABT-627 or A192621 significantly decreased cardiac hypertrophy in rats with congestive heart failure. In conclusion, in sham controls endothelin-B receptor mediated vasodilation and natriuresis, probably as a result of tubular action, whereas in congestive heart failure the excretory contribution of endothelin-B receptor was attenuated, resulting in Na+ retention.
Francis
Bahaa'
B
Department of Physiology and Biophysics, and Rappaport Family Institute for Research in Medical Sciences, Bruce Rappaport Faculty of Medicine, Technion, Haifa, Israel.
Winaver
Joseph
J
Karram
Tony
T
Hoffman
Aaron
A
Abassi
Zaid
Z
D000818:Animals; D000077868:Atrasentan; D001794:Blood Pressure / Q000187:drug effects; D006332:Cardiomegaly / Q000209:etiology / Q000517:prevention & control; D004195:Disease Models, Animal; D065130:Endothelin A Receptor Antagonists; D065131:Endothelin B Receptor Antagonists; D019332:Endothelin-1 / Q000378:metabolism; D006333:Heart Failure / Q000150:complications / Q000188:drug therapy* / Q000378:metabolism / Q000503:physiopathology; D006439:Hemodynamics / Q000187:drug effects*; D015918:Infusion Pumps, Implantable; D007668:Kidney / Q000187:drug effects* / Q000378:metabolism / Q000503:physiopathology; D008297:Male; D009318:Natriuresis / Q000187:drug effects; D011759:Pyrrolidines / Q000008:administration & dosage / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D044022:Receptor, Endothelin A / Q000378:metabolism; D044023:Receptor, Endothelin B / Q000378:metabolism; D013997:Time Factors; D014661:Vasoconstriction / Q000187:drug effects; D014664:Vasodilation / Q000187:drug effects
C120508:A 192621; D065130:Endothelin A Receptor Antagonists; D065131:Endothelin B Receptor Antagonists; D019332:Endothelin-1; D011759:Pyrrolidines; D044022:Receptor, Endothelin A; D044023:Receptor, Endothelin B; D000077868:Atrasentan