ABC | Volume 110, Nº3, March 2018

Original Article Lemos et al Exercise improves splenic arterioles In SHR Arq Bras Cardiol. 2018; 110(3):263-269 Further analysis showed a significant association between sympathetic effect and area of outer wall thickness (r = 0.67, p < 0.005; Figure 3A), sympathetic effect and total area thickness (r = 0.52, p < 0.05; Figure 3B), sympathovagal index and area of outer wall thickness (r = 0.72, p < 0.001; Figure 3C) and sympathovagal index and total area thickness (r = 0.64, p < 0.005; Figure 3D). Discussion Our main findings confirmed the efficacy of exercise training to attenuate sympathetic overactivity and to lower AP in hypertensive animals, showing, in addition, that the training- Figure 2 – Effects of exercise training on the tonic autonomic control of the heart rate (HR) in non-anesthetized rats. (2A) vagal and (2B) sympathetic effects were obtained, respectively, by the difference between vagal blockade (by atropine) or sympathetic blockade (by propranolol) and resting HR. (2C) Sympathovagal balance was expressed by the tonic sympathovagal index, which is the ratio between resting and intrinsic HR (iHR). (2D) Intrinsic HR (bpm) obtained after autonomic double pharmacological blockade. Bars represent mean ± SD. *p < 0.05 vs. WKY S ; † p < 0.05 vs. WKY T and ‡ p < 0.05 vs. SHR S . 100 80 60 40 20 0 Vagal effect Sympathovagal index Intrinsec heart rate Sympathetic effect ∆ HR (bpm) ∆ HR (bpm) IHR (bpm) 1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0.0 WKT S WKT T SHT T SHT S WKT S WKT T SHT T SHT S 0 –20 –40 –60 –80 –100 –120 –140 400 300 200 100 0 *†‡ ‡ *† *† *† *† * (C) (A) (D) (B) Table 1 – Values related to morphological analysis of the area of the wall thickness of splenic arterioles. Thickness area WKY S (n = 10) WKY T (n = 10) SHR S (n = 10) SHR T (n = 10) Inner wall (µm 2 ) 60.5 ± 3.4 58.8 ± 2.3 87.3 ± 3.3* † 58.0 ± 2.6 ‡ Outer wall (µm 2 ) 419.8 ± 29.3 405.6 ± 21.7 632.4 ± 29.1* † 418.8 ± 16.4 ‡ Total area (µm 2 ) 335.6 ± 44.7 349.7 ± 35.8 502.7 ± 36.3* † 332.1 ± 16.0 ‡ Data are expressed as mean ± SD. Abbreviations: WKY S , sedentary normotensive rats; WKY T , trained normotensive rats; SHR S , sedentary hypertensive rats; SHR T , trained hypertensive rats. Data expressed as mean ± SEM.*p < 0.05 vs. WKY S ; † p < 0.05 vs. WKY T and ‡ p < 0.05 vs. SHR S . induced, sympathetic-lowering effect was associated with normalization of abnormal splenic artery diameter, decreasing the degree of vascular injury in spleen. The morphometric analysis of small vessels employed in the present study revealed that the splenic vascular adjustments are specific for the SHR T . It is well documented that chronic physical exercise attenuates sympathetic hyperactivity 10 and arteriolar damage on hypertension. 17 To our knowledge, however, this is one of the first reports to evidence association between a reduction in splenic arteriole injury and sympathetic activity. The cause-effect relation between hypertension and arteriolar damage (hypertrophy) is well established. 18-20 In this sense, the literature evidences that an effective 266