Disfunção vasodilatadora em pacientes com doença renal crônica

Abstract

INTRODUCTION: In chronic kidney disease, studies have shown an imbalance between vasoconstrictor and vasodilator mechanisms. These findings may be reflect increased resting vasoconstriction and blunted reflex muscle vasodilatory response during exercise. The goal of the present study was to test the hypothesis that non-dialysis chronic kidney disease patients have an decreased forearm vascular conductance at rest and blunted vasodilatory response during exercise. METHODS: Nine non-dialysis chronic kidney disease patients were evaluated (CKD group, 44 ± 5 yr). An age-matched healthy subjects group (Control group, n = 12, 36 ± 5 yr) was also studied. Blood pressure (oscillometry - DIXTAL2023), heart rate (ECG - DIXTAL2023) and forearm blood flow (venous occlusion plethysmography - Hokanson) were recorded simultaneously at rest, during passive exercise, isometric exercise at 10 and 30% of maximum voluntary contraction (MVC) protocols (3 minutes baseline followed by 3 minutes of exercise) and post-exercise circulatory arrest (2 minutes). Forearm vascular conductance was calculated dividing the forearm blood flow by mean blood pressure. RESULTS: At rest, blood pressure levels were significantly higher in the CKD group when compared with the Control group. Baseline forearm blood flow was similar between groups, but baseline forearm vascular conductance was significantly lower in the CKD group when compared with the Control group. During passive exercise and isometric exercise at 10% MVC, blood pressure, heart rate, forearm vascular blood flow and forearm vascular conductance responses were similar between groups. In these protocols, forearm blood flow was similar between groups, however the CKD group had blood pressure levels significantly higher and forearm vascular conductance significantly lower when compared with the Control group. During isometric exercise at 30% MVC, blood pressure and heart rate responses were similar between groups. In this protocol, the CKD group has presented blood pressure significantly higher and forearm vascular conductance significantly lower when compared with the Control group. Forearm blood flow and forearm vascular conductance responses differ between groups (Interaction effect: p=0.008 and p=0.026, respectively). The CKD group showed significantly blunted reflex muscular vasodilatory response when compared with the Control group. The blood pressure response was similar between groups during post-exercise circulatory arrest, although the CKD group has presented significantly increased blood pressure. CONCLUSION: Non-dialysis chronic kidney patients have significantly decreased forearm vascular conductance at baseline and blunted muscular vasodilatory response during exercise.