Influence of specific and non-specific endothelin receptor antagonists on renal morphology in rats with surgical renal ablation.
BACKGROUND
Studies in experimental models of chronic renal failure suggest an important role for the endothelin system in the development of renal scarring. Endothelin receptor (ETR) anatagonists interfere with progression, but it has not been resolved (i) whether this is true for all models of renal damage, (ii) to what extent the effect is modulated by systemic blood pressure and (iii) whether the effect is similar for ETAR and ETA/ETBR antagonists.


METHODS
5/6 subtotal nephrectomy (SNX) by surgical ablation in male Sprague-Dawley rats. Comparison of ACE inhibitor Trandolapril (0.1 mg/kg/day), ETAR antagonist BMS 182874 (30 mg/kg/day) and ETAR/ETBR antagonist Ro 46-2005 (30 mg/kg/day) by gavage. Duration of the experiment eight weeks.


METHODS
Systolic blood pressure by tail plethysmography. Perfusion fixation of kidneys and morphometric analysis ET-1 and ETA/ETBR by quantitative PCR.


RESULTS
SNX caused a significant (P < 0.01) increase of systolic blood pressure (170 +/- 8.6 mmHg) compared to sham operated controls (131 +/- 5.3 mmHg). Blood pressure was significantly (P < 0.001) lower with Trandolapril (128 +/- 5.3 mmHg), but not with BMS 182874 (153 +/- 5.9 mmHg) or Ro 46-2005 (167 +/- 7.6 mmHg). Compared to sham operated rats (0.03 +/- 0.01) glomerulosclerosis index (GSI) was significantly (P < 0.01) higher in the untreated SNX group (0.9 +/- 0.15). Significantly lower GSI was found in Trandolapril treated (0.29 +/- 0.04), BMS 182874 treated (0.36 +/- 0.05), and Ro 46-2005 treated animals (0.45 +/- 0.11). The effect of BMS 182874 was accompanied by lower tubulointerstitial damage index. Mean glomerular volume was dramatically increased (P < 0.001) in SNX rats as compared to sham operated animals. This glomerular enlargement was partially prevented by Trandolapril (P < 0.05), but not by either ETR antagonist. ET-1 mRNA tended to be higher in SNX irrespective of treatment, while ETAR and ETBR mRNA were significantly lower.


CONCLUSIONS
Both specific (ETAR) and non-specific (ETA/ETBR) endothelin antagonists interfere with development of glomerulosclerosis by mechanisms which are, at least in part, independent of systemic blood pressure.
Nabokov
A
A
Department of Internal Medicine, University of Heidelberg, Germany.
Amann
K
K
Wagner
J
J
Gehlen
F
F
Münter
K
K
Ritz
E
E
D000806:Angiotensin-Converting Enzyme Inhibitors / Q000494:pharmacology; D000818:Animals; D000959:Antihypertensive Agents / Q000494:pharmacology*; D001483:Base Sequence; D001794:Blood Pressure / Q000187:drug effects; D017931:DNA Primers / Q000737:chemistry; D003619:Dansyl Compounds / Q000494:pharmacology*; D065128:Endothelin Receptor Antagonists; D016232:Endothelins / Q000235:genetics / Q000378:metabolism; D005923:Glomerulosclerosis, Focal Segmental / Q000378:metabolism / Q000473:pathology* / Q000517:prevention & control; D006984:Hypertrophy; D007211:Indoles / Q000494:pharmacology; D007678:Kidney Glomerulus / Q000187:drug effects / Q000378:metabolism / Q000473:pathology*; D008297:Male; D008969:Molecular Sequence Data; D009392:Nephrectomy; D016133:Polymerase Chain Reaction; D011743:Pyrimidines / Q000494:pharmacology*; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D017466:Receptors, Endothelin / Q000235:genetics; D013449:Sulfonamides / Q000494:pharmacology*; D000096926:Benzenesulfonamides
D000806:Angiotensin-Converting Enzyme Inhibitors; D000959:Antihypertensive Agents; D017931:DNA Primers; D003619:Dansyl Compounds; D065128:Endothelin Receptor Antagonists; D016232:Endothelins; D007211:Indoles; D011743:Pyrimidines; D012333:RNA, Messenger; D017466:Receptors, Endothelin; D013449:Sulfonamides; C083751:Ro 46-2005; D000096926:Benzenesulfonamides; C085754:5-(dimethylamino)-N-(3,4-dimethyl-5-isoxazolyl)-1-naphthalenesulfonamide; C052035:trandolapril