title: Stereology of the myocardium in hypertensive rats. Differences in relation to the time of inhibition of nitric oxide synthesis.
abstract: Structural changes in the myocardium following inhibition of nitric oxide synthesis were studied quantitatively within two different periods. Four groups of 10 rats were studied: control and L-NAME (NG-nitro-methyl-ester-L-arginine) groups for 25 and for 40 days. L-NAME was administered at 50 mg/kg per day in the drinking water. On the 26th and 41st days, the hearts were examined. Volume densities of myocytes (Vv[m]), cardiac interstitium (Vv[int], numerical density of myocytes (Nv[m]) and mean cross-sectional area of the myocytes (A[m]) were determined. Comparing the L-NAME animals with their respective controls showed the arterial pressure (AP) and the heart weight (HW) to be increased in the L-NAME animals. At 25 days, and more obviously at 40 days, the myocytes were hypertrophied with increase of myofibrils (A[m], greater in L-NAME rats). There were some areas with ischaemic lesions, inflammatory infiltrates and perivascular and interstitial fibrosis. The intramyocardial arteries had a thick tunica media and tunica intima. At 25 days the myocardium showed no stereological difference between L-NAME and controls, but by 40 days there was decreased Vv[m] and Nv[m] and increased Vv[int] in the exposed group. Inhibition of NO synthesis provoked a time progressive myocardial change, quantified by stereology.
authors.affiliation: Universidade do Estado do Rio de Janeiro, Centro Biomédico, Instituto de Biologia, Laboratório de Morfometria & Morfologia Cardiovascular, RJ, Brazil.
authors.forename: L M
authors.initials: LM
authors.lastname: Pereira
authors.forename: G M
authors.initials: GM
authors.lastname: Vianna
authors.forename: C A
authors.initials: CA
authors.lastname: Mandarim-de-Lacerda
mesh_terms: D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D002452:Cell Count; D003331:Coronary Vessels / Q000473:pathology; D004195:Disease Models, Animal; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D006321:Heart / Q000187:drug effects; D006973:Hypertension / Q000139:chemically induced / Q000473:pathology*; D008297:Male; D018715:Microscopy, Video; D009206:Myocardium / Q000201:enzymology / Q000473:pathology*; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology*; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors* / Q000378:metabolism; D009929:Organ Size / Q000187:drug effects; D051381:Rats; D017208:Rats, Wistar; D013997:Time Factors
chemical_list: D004791:Enzyme Inhibitors; D019001:Nitric Oxide Synthase; D019331:NG-Nitroarginine Methyl Ester