Temporal Evaluation of Baroreflex Dysfunction: Role in Target Organ Damage

Abstract

Wistar rats were divided into 5 groups: control, D1(24h), D2(28 days), D3 (90 days) and D4 (6 months). Sinoaortic denervation (D) was used as a model of arterial baroreflex deficit. BP, HR were analysed using a data acquisition system. Cardiac output (CO) and tissues blood flow were evaluated using microspheres. BP and the HR was incresed in D after 24h (C:106 ± 0.6 vs. D1: 142 ± 2 mmHg; C: 355 ± 7 vs. D1: 453 ± 10 bpm), but it were normalizaed in chronic D. Moreover, it was observed a gradual reduction over time in CO (C: 111 ± 7, D1:81±5, D2:85 ± 6, D3:69±5 D4:35±2 mL/min) accompanied by an increase in total peripheral resistance (C:0.97±0.07, D1:1.74±0.05, D2:1.23±0.07, D3:1.60±0.09, D4:3.00±0.05 mL/min/mmHg) in D groups. Those alterations resulted in a decreased renal blood flow (C:3.47±0.21, D1:1.37±0.19, D2:1.49±0.18, D3:1.12±0.13, D4:0.42±0.16 mL/min/g), coronary flow (C:2.91±0.71, D1:2.07±0.19, D2:1.58±0.28, D3:0.92±0.13, D4:0.34±0.16 mL/min/g) and muscle flow (C:0.24±0.02, D1:0.08±0.005, D2:0.10±0.02, D3:0.05±0.01, D4:0.05±0.007 mL/min/g) in D groups. The acute total baroreflex dysfuntion incresed BP and HR and reduced blood flow and cardiac output, these changes are associated with the body’s attempt to maintain homeostasis. However, was observed a progressive reduction in CO and regional flow associated with an increase in RPT. These adjustements may play an important role in target organ-damage.