Beneficial effect of enalapril in spontaneously hypertensive rats cardiac remodeling with nitric oxide synthesis blockade.
OBJECTIVE
To study the efficiency of an angiotensin converting enzyme inhibitor on the blood pressure (BP) and the myocardium remodeling when spontaneously hypertensive rats (SHRs) are submitted to nitric oxide synthesis (NOs) blockade (with L-NAME) and simultaneously treated.


METHODS
Young adult male SHRs were separated in four groups (n = 5) and treated for 20 days: Control, L-NAME, L-NAME+Enalapril, and Enalapril. The alterations of the BP, heart mass/body mass ratio and stereological parameters for myocytes, connective tissue and intramyocardial vessels were studied among the groups.


RESULTS
The SHRs with NOs blockade showed a great modification of the myocardium with extensive areas of reparative and interstitial fibrosis and accentuated hypertrophy of the cardiac myocytes (cross sectional area 60% higher in animals taking L-NAME than in Control SHRs). Comparing the SHRs with NO deficiency (L-NAME group), the Control SHRs and the Enalapril treated SHRs significant differences were found in the BP and in all stereological parameters. The NO deficiency caused an important BP increment in SHRs that was partially attenuated by Enalapril. This Enalapril effect was more pronounced in Control SHRs. A significant increment of the intramyocardial vessels was observed in NO deficient SHRs and Control SHRs treated with Enalapril demonstrated by the stereology (greater microvascular densities in treated SHRs).


CONCLUSIONS
Enalapril administration showed a beneficial effect on vascular remodeling and myocardial hypertrophy in SHRs. In SHRs with NO blockade, however, the beneficial effect of Enalapril occurred only in vascular remodeling.
de Andrade Zorzi
R L
RL
Laboratory of Morphometry & Cardiovascular Morphology, Biomedical Center, State University of Rio de Janeiro, Rio de Janeiro, RJ, Brasil.
Meirelles Pereira
Leila M
LM
Mandarim-de-Lacerda
C A
CA
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D004357:Drug Synergism; D004656:Enalapril / Q000494:pharmacology* / Q000627:therapeutic use*; D006321:Heart / Q000187:drug effects*; D006973:Hypertension / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D008297:Male; D009206:Myocardium / Q000201:enzymology / Q000378:metabolism / Q000473:pathology; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009569:Nitric Oxide / Q000378:metabolism*; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors* / Q000378:metabolism; D051381:Rats; D011918:Rats, Inbred SHR
D009569:Nitric Oxide; D004656:Enalapril; D019001:Nitric Oxide Synthase; D019331:NG-Nitroarginine Methyl Ester