Influência do treinamento físico na disfunção ventricular direita de ratos expostos cronicamente à fumaça de cigarro

Abstract

Smoking is responsible for developing co-morbidities with high contribution to mortality, and result in cardiac remodeling. However, the benefits exercise lead to the cardiovascular system such as physiological cardiac hypertrophy, vascular and cardiac growth of capillaries; thus, physical training-provided benefits have potential to attenuate smoking harmful effects to the heart. This study is aimed to assess structural and functional relationships of hearts in rats exposed to smoke of cigarette, as well as assess the influence of physical training with smoke. Fourty Wistar rats were used and distributed into four groups (n = 10, each): control (C), smokers (S), trained control (TC), and trained smokers groups. All groups were followed up for 3 months. All animals were weighted at each week and fed daily, the hemodynamics measurements were carried out through right ventricle catheterization, and then followed by volumetric overloading analysis through infusion. It was found statistically significant increased final body weight for C group compared with S, TC and TS groups (p < 0.05). For right ventricle maximum systolic pressure (RV-maxSP), right ventricle initial diastolic pressure (RVIDP), and right ventricle final diastolic pressure (RVFDP) variables, there was statistically significant increase between S and TS groups compared with C and TC groups, respectively (p<0,05). Comparing ST and TC groups there was significant decrease (p<0.05) for the derivate maximum pressure over time (+dP/dt) and derivate minimum pressure over time (-dP/dt) and systolic duration (SD). The heart frequency (HF) for S group increased statistically when compared with C and TS groups (p<0.05), as well as between TS and TC groups (p<0.05). Immediately after infusion, the volumetric overload test values showed statistically significant difference between TS and TC groups (p<0.05) for RVmaxSP, RVIPD, RVFDP, diastolic duration (DD) and HF; It were found statistically increased values between S and C groups (p<0.05) for FDP and HF; however, the S group had HF values statistically higher than TS group (p<0.05). Analyzing +dP/dt and –dP/dt there was statistically decrease between TC and S groups (p<0.05). This analysis was repeated 10 minutes after infusion and found statistic increase for RVmaxSP and RVFDP values between TS and S groups, as well as between TC and C groups, respectively (p<0.05). The TS group showed statistically significant decrease of +dP/dt and –dP/dt values when compared with S and C groups. There was statistically decrease of HF values when TS and S groups were compared with (p<0,05). It were found increased values of wet weight for right ventricle (RV), left ventricle (LV), and lungs, all of which were corrected by body weight and showed statistically difference between TC and C groups (p<0.05). The TS group showed statistically significant values of RV compared with S group, however S group had LF values higher than C group. The TC group showed statistically increased values of lungs when compared with TS group (p<0.05). It was noted increased fluid retention with statistic difference for RV, LV and lungs when S group was compared with ST and C groups (p<0.05). In conclusion, the chronic exposure to cigarette smoke provoked right ventricle dysfunction, changes of hemodynamics variables and heart remodeling. The magnitude and physical training load stipulated on protocol of swimming did not provide benefits to attenuate aggressive effects of chronic exposure to cigarette smoke on functional parameters. There was beneficial influence of physical training on morphometric parameters of heart, lung, and heart frequency.