Enhanced vasoconstrictor sensitivity to exercise pressor reflex engagement in peripheral arterial disease (1156.7)

Abstract

Exercise is associated with a rise in heart rate, blood pressure (BP) and blood flow to active muscle mediated by the exercise pressor reflex and regional release of vasodilators. In peripheral arterial disease (PAD) the exercise pressor reflex is enhanced. To assess the functional impact of the exercise pressor reflex, we determined BP and mean blood velocity (MBV, Doppler) in the popliteal artery and calculated vascular conductance (VC, MBV/mean BP) in the exercising and contralateral legs during graded rhythmic plantar flexion in 7 patients with PAD (age 67±2 yrs, ankle‐brachial‐index 0.6±0.1 in the ischemic leg) and in 5 controls. At peak exercise (2.0 kg, 1 Hz), the pressor effect was greatest in PAD when exercise was performed with the ischemic leg, and lowest in the controls. In controls, exercise did not affect VC in the contralateral inactive leg (P=NS). Similarly, in PAD, exercise in the ischemic leg did not affect VC in the opposite inactive leg (P=NS). In contrast, during exercise with the non‐ischemic leg, VC in the contralateral ischemic leg decreased by 24±10% (P<0.05). Thus, activation of the exercise pressor reflex resulted in vasoconstriction in the inactive but diseased leg. This suggests that despite upregulation of peripheral vasodilator factors, the vasculature of the ischemic leg is exquisitely sensitive to reflex vasoconstriction.Grant Funding Source: Supported by P01 HL096570 and UL1 TR000127