Aerobic Training (T) Improves Microcirculatory Profile in Brain Areas of Normotensive (WKY) and Spontaneously Hypertensive Rats (SHR)

To evaluate the effects of hypertension and T in the microcirculatory profile within autonomic areas, WKY and SHR were submitted to treadmill T (55% of maximum capacity, 1h/day, 5 d/week) or kept sedentary (S) for 3 months. After hemodynamic measurements at rest, rats were anesthetized for FITC‐dextran administration (1 ml of 5% solution). Brains were removed, post‐fixed and sliced (25 μm) for analysis of the capillary volume (Image ProPlus + 3D‐construction) within the NTS and hypothalamic paraventricular nucleus (PVN). SHR vs. WKY exhibited elevated MAP and HR (180±2 mmHg, 359±6 b/min). Capillary volume (expressed as ×10 −3 μm 3 /μm 3 tissue) was similar in WKY‐S and SHR‐S but differed between autonomic areas being larger into the PVN (ventromedial=14.15±1.27, posterior=6.72±0.56) and smaller into the NTS (2.51±0.14). T improved treadmill performance and resting bradycardia (−9%) in both groups; pressure fall (−8%) was only observed in the SHR. T caused marked increase in capillary volume in all autonomic areas (ventromedial: +91% and +74%; posterior: +20% and +21%; NTS: +41% and +27%, for WKY and SHR respectively). Contrary to the peripheral microcirculatory response, hypertensive brain capillaries showed no rarefaction within autonomic areas. Data also showed a large T‐induced capillary angiogenesis in both groups, therefore improving brain perfusion after training. Financial Support: CAPES, FAPESP