Heart biometry and allometry in rats submitted to nitric oxide synthesis blockade and treatment with antihypertensive drugs

Fifty mature male rats were separated into groups of ten rats each (control, L-NAME, spironolactone, enalapril and verapamil). On the 41st day of experimentation, animals were anesthetized, weighed and sacrificed. The tail blood pressure (TBP) was 76% higher in L-NAME group than in the control group. Spironolactone, enalapril and verapamil were efficient in reducing TBP in those respective groups of rats (spironolactone was less efficient in reducing TBP). The heart mass/body mass ratio (HBR) increased 24% in L-NAME group and spironolactone group. No differences in HER were found when control animals and animals treated with enalapril and verapamil were compared. Heart volume (HV) was greater in L-NAME group than other groups, but it was not different comparing the L-NAME and the spironolactone groups. The left ventricle was responsible for the changes in the HV. The relationship between the HV and the body mass (BM) was not significant in the groups L-NAME and spironolactone. However, this relationship was significant and allometric in control, enalapril and verapamil groups. In control group, HV had a positive allometric tendency against the BM, but in the enalapril and verapamil groups this tendency was allometrically negative. Cardiac hypertrophy in rats under inhibition of NO synthesis was prevented by treatment with enalapril and verapamil more efficiently than spironolactone.