title: Myocyte loss in early left ventricular hypertrophy of experimental renovascular hypertension.
abstract: Left ventricular hypertrophy (LVH) develops very early in experimental renovascular hypertension after clipping of one renal artery and is accompanied by a remodeling of cardiac structure which has not yet been investigated in detail. It was the aim of the present study to analyze changes in cardiomyocyte number and volume in LVH after 2 weeks of renovascular hypertension. Sprague-Dawley rats were subjected to clipping of the left renal artery (2K1C) or sham operation (sham). One group of 2K1C rats received antihypertensive treatment with dihydralazine. The experiment was terminated after 2 weeks. Hearts were investigated using stereological methods, electron microscopy, immunohistology for the proliferation marker proliferating cell nuclear antigen, the pro- and anti-apoptotic proteins Bax and Bcl-2 as well as the TUNEL technique. After 2 weeks, systolic blood pressure and relative left ventricular weight were significantly higher in untreated 2K1C animals than in sham and dihydralazine-treated 2K1C rats. Volume fraction of interstitial tissue and capillary length density were not different, whereas wall thickness of intramyocardial arteries was significantly higher in untreated 2K1C (5.12+/-0.7 micro m) than in sham (3.92+/-0.6 micro m) and in dihydralazine-treated 2K1C (3.91+/-0.7 micro m) rats. Cardiomyocyte diameter and volume were significantly higher in untreated 2K1C than in sham animals. The number of cardiomyocytes per left ventricle was significantly lower in untreated 2K1C rats (5.5+/-1.6 vs 3.9+/-6.9 x10(7)). Using immunohistochemistry, no direct evidence of apoptosis was found, but a relative higher expression of the anti-apoptotic protein bcl-2 expression was seen in untreated 2K1C than in sham animals. This may reflect a protective mechanism as a consequence of earlier occurring apoptosis. These observations document that experimental renovascular hypertension induces a rapidly developing LVH characterized by marked cardiac remodeling and substantial loss of cadiomyocytes.
authors.affiliation: Department of Pathology, University of Heidelberg, Germany.
authors.forename: Moriz
authors.initials: M
authors.lastname: Buzello
authors.forename: Christoph
authors.initials: C
authors.lastname: Boehm
authors.forename: Stephan
authors.initials: S
authors.lastname: Orth
authors.forename: Bernhard
authors.initials: B
authors.lastname: Fischer
authors.forename: Heimo
authors.initials: H
authors.lastname: Ehmke
authors.forename: Eberhard
authors.initials: E
authors.lastname: Ritz
authors.forename: Gerhard
authors.initials: G
authors.lastname: Mall
authors.forename: Kerstin
authors.initials: K
authors.lastname: Amann
mesh_terms: D000818:Animals; D000959:Antihypertensive Agents / Q000627:therapeutic use; D017209:Apoptosis; D001794:Blood Pressure / Q000187:drug effects; D002452:Cell Count; D004078:Dihydralazine / Q000627:therapeutic use; D004195:Disease Models, Animal; D006352:Heart Ventricles / Q000187:drug effects / Q000648:ultrastructure; D006978:Hypertension, Renovascular / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology*; D017379:Hypertrophy, Left Ventricular / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology*; D007150:Immunohistochemistry; D020287:In Situ Nick-End Labeling; D008297:Male; D032383:Myocytes, Cardiac / Q000187:drug effects / Q000378:metabolism / Q000473:pathology*; D009929:Organ Size; D018809:Proliferating Cell Nuclear Antigen / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D051028:bcl-2-Associated X Protein
chemical_list: D000959:Antihypertensive Agents; C494828:Bax protein, rat; D018809:Proliferating Cell Nuclear Antigen; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D051028:bcl-2-Associated X Protein; D004078:Dihydralazine