Numerical Density of Cardiomyocytes in Chronic Nitric Oxide Synthesis Inhibition

Abstract

Objective: The myocardial effect on the normalization of arterial blood pressure in animals with hypertension previously induced by nitric oxide synthesis (NOS) inhibition is still unknown. The purpose of this study was to estimate the numerical density of cardiomyocytes that is able to show cardiomyocyte loss as a consequence of NOS inhibition. Methods: Sixty rats were divided into the following groups: control for 25 days (C25), control for 40 days (C40) control for 80 days (C80) and three other groups in which the rats received the NOS inhibitor N(G)-nitro-L-arginine-methyl-ester hydrochloride L-NAME; 50 mg/kg/day for 25 days (L25), 40 days (L40) and 40 days, respectively, the latter group having another 40 days of only water and food ad libitum (without L-NAME; L80 group). The detection of apoptotic cells was performed using a monoclonal antibody. Results: In the L25, L40 and L80 groups, blood pressure was 74.5, 90.2 and 56.3% higher than the respective age-matched control rats, the myocardium had hypertrophy of the cardiomyocytes and scattered areas of fibrosis, and apoptosis occurred in isolated cells. Compared to the controls, the heart mass/body mass ratio was significantly greater in the L-NAME groups L25, L40 and L80, i.e. 31, 26 and 21%, respectively, the numerical density of cardiomyocytes in L-NAME rats was 32.7, 48.8 and 41.7% lower and the mean volume of cardiomyocytes was 33, 53 and 48% greater. Conclusion: The cardiomyocyte loss in NOS inhibition seems to be mainly due to necrosis, although apoptosis is also present.

Stereological tools in biomedical research

“…Counts are made into a frame of known area A T (considering the forbidden line and its extensions like described before). So, a test-volume is constructed (A T multiplied by thickness), count into this test-volume is considered unbiased (Gundersen et al 1988a, Mandarim-de-Lacerda and Costa 1993, Mandarim-de-Lacerda et al 1995, Burity et al 1996, Aguila and Mandarim-de-Lacerda 1999, Mandarim-de-Lacerda and Pereira 2000, Pessanha and Mandarim-de-Lacerda 2000, Melo et al 2002. The optical disector consists of counts made in thick sections observed with a light microscope adapted with axis-z mobile stage (to exactly determine the distance between up and down planes of the disector, or thickness t).…”

Volume-weighted mean nuclear volume and numerical nuclear density in the cardiomyocyte following enalapril and verapamil treatment

“…The chronic deficiency of nitric oxide (NO) causes arterial hypertension accompanied by cardiac hypertrophy, loss of cardiomyocytes, and changes in the myocardial microcirculation [19,25,26,27,28,29]. However, there is still controversy in relation to the exact interpretation of myocardial alterations caused by this model of arterial hypertension [23].…”

Effects of Virgin Coconut Oil on the Histomorphometric Parameters in the Aortae and Hearts of Rats Fed with Repeatedly Heated Palm Oil

“…In addition to those reports, Ref. [41], [42] suggested that dilation and myocyte hyperplasia may be associated with the process of cardiac tissue remodeling. Reference [12] has reported chronic consumption of reheated palm oil induced cardiac toxicity but on the other hand, [43] suggested those events could be the results of toxicant production that had been induced by the lipid peroxidation of the palm oil.…”