Resistance exercise and testosterone treatment alters the proportion of numerical density of capillaries of the left ventricle of aging Wistar rats.

UNLABELLED: Changes in the heart compartments that leads to pathological cardiac hypertrophy can be related to testosterone reduction in aging males since heart cells are susceptible to androgens. Resistance exercise delays the changes of aging. AIM: This study aimed to analyze alterations of the left ventricle of aged rats subjected to resistance exercise with administration of testosterone. METHODS: Wistar rats were divided into five groups: C Group (control), S Group (sedentary), ST Group (sedentary treated with testosterone), T Group (trained) and TT Group (trained and treated with testosterone), strength training protocol and testosterone treatment were 16 weeks long. All groups were sacrificed at 16 months except for C group, sacrificed at 13 months. RESULTS: There was no change in the weight of the heart or the left ventricle between the groups. ST group showed increase in Nv [cap] density of capillaries and collagen, with no differences in interstitial space. Both trained groups (T and TT) showed increase in the numerical density of capillaries (Nv [cap]) and in the interstitial space, with no changes in collagen. CONCLUSION: Resistance exercise combined with testosterone triggered a response of compensatory adjustment in the increase of Nv [cap], collagen and interstitial space, increasing perfusion and nutrition to the heart.

Atrazine-induced changes in the myocardial structure of peripubertal rats.

The aim of the present study was to investigate the effect of atrazine (6-chloro-N(2)-ethyl-N(4)-isopropyl-1,3,5-triazine-2,4-diamine) on the left ventricle myocardium in juvenile/peripubertal male Wistar rats. Atrazine was administered orally at 50 or 200 mg/kg of body weight dose for 28 consecutive days. In order to assess possible structural alterations, tissue sections were examined histologically and then subjected to quantification analysis using stereological methods. The tissue specimens were routinely processed and stained with Mallory trichrome method in order to clearly distinguish muscle cells from the connective tissue components. A toluidine blue staining method was additionally used for the demonstration of mast cells. Statistically significant increase in length density and numerical density of capillaries were found at both the investigated doses of atrazine compared with the control. The increase in surface density and volume density of capillaries found at lower dosage of atrazine was significant in comparison with the control. The extensive mast cell degranulation was noted on the histological examination at both doses of the applied chemical. No significant changes were demonstrated for the stereological parameters of cardiomyocytes. Based on the available published data and the present results, it can be concluded that atrazine promoted angiogenesis in the rat myocardium, which might be partially mediated by mast cells.