Prolonged Walking Attenuates Hypersympathetic State In Swine With Bilateral Femoral Artery Occlusion

Abstract

An increased sympathoexcitation state (SES) has been found in patients with peripheralarterial disease (PAD). Symptoms include an exaggerated response of blood pressure (BP) during increasing physicalactivity. This high SES is detrimental to PAD patients. To determine whether physical training could alleviate SES, 11 Yucatan male pigs received bilateral femoral artery occlusion (BiFemOccl), and were either limited to cage activity (Sed, n=5) or walkedabout 30 min/d (3 mph) on treadmill for 12 wks (Tr, n=6). Arterial baroreflex function was assessed by intravenously infusing adenosine to trig sympathetic drive (1.5 mg /kg) or phenyleprine (PE, 0.1 mg/kg) for parasympathetic drive. BP and heart rate (HR) were recorded through a catheter in the thoracic aorta while animals stood on treadmill. Net change of HR was calculated to change of BP in each animal. Even though resting BP (125 ±5 mm Hg) and HR (110±5 bpm) showed no differences between Sed and Tr group at either prior or post training, the slopes of HR response to reduce BP by adenosine were ‐1.08±0.22 and ‐0.57±0.03 for Sed and Tr group respectively (p<0.05). The HR responses to increased BP by PE were similar between Sed and Tr groups (Slope ‐0.71 ±0.04). The results indicate that swine with BiFemOccl shows exaggerated HR response to baroreceptor unloading and the high SES can be tempered by exercise training. Thus, a chronic exercise program could provide benefit to patients with PDA by reducing the risk of cardiovascular accidents due to the high SES.Supported by NIH grant P01 HL 52490.