Effects of endothelin receptor antagonism and angiotensin-converting enzyme inhibition on cardiac and renal remodeling in the rat.
The effects of a nonpeptide, orally active mixed endothelin (ET) ETA/ETB receptor antagonist, SB 217242, and an angiotensin-converting enzyme (ACE) inhibitor, ramipril, were evaluated after inter-renal aortic banding in the rat. Separate sham, vehicle, and treatment groups were compared in each study. In vehicle-treated animals in the ramipril group, aortic banding for 4 weeks produced significant cardiac hypertrophy (247 +/- 5 mg/100 g bw vs. 305 +/- 11 mg/100 g bw; p < 0.001), right (upstream) renal hypertrophy (380 +/- 6 mg/100 g bw vs. 559 +/- 28 mg/100 g bw; p < 0.001), and significant left (downstream) renal atrophy (405 +/- 4 mg/100 g bw vs. 192 +/- 25 mg/100 g bw; p < 0.001). Continuous ramipril treatment (1 mg/kg p.o. once daily), begun 3 days before aortic banding, inhibited cardiac hypertrophy (305 +/- 11 mg/100 g bw vs. 266 +/- 7 mg/100 g bw; p < 0.05) but did not alter renal hypertrophy or atrophy. In a similarly designed study, SB 217242 (30 mg/kg p.o. b.i.d.) had no effect on the development of cardiac hypertrophy (298 +/- 7 mg/100 g bw vs. 310 +/- 12 mg/100 g bw) or renal hypertrophy (561 +/- 15 mg/100 g bw vs. 575 +/- 19 mg/100 g bw), but abolished the development of renal atrophy (158 +/- 16 mg/100 g bw vs. 395 +/- 19 mg/100 g bw; p < 0.001). [125I]ET-1 radioligand binding experiments indicated that the density of both ETA and ETB receptors was increased dramatically (three- to fourfold) in the atrophic kidney cortex compared to sham or hypertrophic kidneys. In situ hybridization studies indicate an upregulation of ETB receptor mRNA in the glomeruli of atrophic kidneys within 5 days of aortic banding. In conclusion, an angiotensin-dependent mechanism may mediate cardiac hypertrophy associated with aortic banding, whereas ET-dependent mechanisms may mediate an atrophic response in the hypoperfused kidney, perhaps through an interaction with upregulated ETA and/or ETB receptors.
Willette
R N
RN
Department of Cardiovascular Pharmacology, SmithKline Beecham Pharmaceutics, King of Prussia, PA 19406, USA.
Minehart
H
H
Ellison
J
J
Simons
T
T
Short
B
B
Pullen
M
M
Ohlstein
E H
EH
Nambi
P
P
D000806:Angiotensin-Converting Enzyme Inhibitors / Q000494:pharmacology*; D000818:Animals; D006332:Cardiomegaly / Q000473:pathology*; D065128:Endothelin Receptor Antagonists; D006984:Hypertrophy; D017403:In Situ Hybridization; D007668:Kidney / Q000187:drug effects / Q000473:pathology*; D007672:Kidney Cortex / Q000187:drug effects / Q000378:metabolism; D008297:Male; D011869:Radioligand Assay; D017257:Ramipril / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D044022:Receptor, Endothelin A; D044023:Receptor, Endothelin B; D017466:Receptors, Endothelin / Q000235:genetics
D000806:Angiotensin-Converting Enzyme Inhibitors; D065128:Endothelin Receptor Antagonists; D044022:Receptor, Endothelin A; D044023:Receptor, Endothelin B; D017466:Receptors, Endothelin; D017257:Ramipril