Efeito da suplementação oral com L-arginina sobre a microcirculação/vasoreatividade, perfis pressórico e metabólico de mulheres jovens e idosas com envelhecimento bem-sucedido, diabetes Mellitus tipo 2 e sarcopenia

Abstract

Introduction: L-arginine is an amino acid involved in several physiological processes, is a precursor of nitric oxide (NO), stimulates insulin secretion and improves endothelial-dependent vasodilation. The reduced bioavailability of L-arginine/NO is associated with the aging process and vascular dysfunction demonstrated by the decrease in vasoreactivity. In senescence, sarcopenia, (loss of muscle mass and decreased muscle function), and Diabetes Mellitus affect more than 50% of the elderly over 80 years, mainly women, increasing cardiovascular morbidity and mortality. Like type 2 Diabetes Mellitus (DM2), sarcopenia is associated with insulin resistance, decreased capillary blood flow and decreased endothelium-dependent vasodilation, but we still do not know the effect of L-arginine on the microcirculation of elderly women with sarcopenia, DM2 compared to elderly women with successful aging. Objective: We investigated the hypothesis that 14 days of supplementation with 5 g of L-arginine would act improving vasoreactivity, microcirculation, blood pressure, as well as glucose and lipid metabolic profiles and renal function in healthy young women and elderly women with healthy aging, DM2 and sarcopenia. Methods: 98 women from State University of Rio de Janeiro , aged 25-30 years and 65 years or older were included and distributed into the following groups: HY (25 healthy young control), HE (25 healthy elderly control) defined by the absence of cognitive deficit and comorbidities except mild arterial hypertension, elderly women with primary sarcopenia (EPS = 25) defined as having a Muscle Mass Index £ 6.37kg/m2 and Hand Grip Strength (HGS) £ 20kgf, elderly women with Type 2 Diabetes Mellitus (EDM2 = 23) defined as having glycated hemoglobin ³ 6.4%, accepting those with mild arterial hypertension using only 1 antihypertensive agent, excluding diuretics. Clinical evaluation, biochemical profiles (glycemic [glucose, Hb], lipid [total cholesterol [CT], triglycerides [TG], high-density lipoprotein [HDLc], low-density lipoprotein [LDLc], and renal function) (creatinine and urea)], evaluation of microcirculation by nailfold videocapillaroscopy - NVC (functional capillary density [FCD], capillary diameters (afferent [AFD], apical [APD] and efferent [EFD]), basal red blood cell velocity [RBCV] , maximal RBCV after 1 minute ischemia in finger [RBCVmax] and time to reach RBCVmax [TVDHmax]) and venous occlusion plethysmography - VOP (basal forearm blood flow, maximal forearm blood flow during 5-minute post occlusion reactive hyperemia [PORH] of the artery) maximal forearm blood flow after application of 0.4mg of sublingual nitroglycerin ) before and after L-arginine supplementation. Body composition evaluation by DXA and HGS were used to characterize sarcopenia. Effect of L-arginine supplementation in each group used Wilcoxon matched pair tests. Intergroups comparison has been done with Kruskal-Wallis and Dunn Tests.Statistical significance with p<0.05 was adopted. Results: L-arginine supplementation did not change glycemic/lipid profiles and renal function in any of the groups evaluated. However, there was a decrease in systolic, diastolic and mean arterial pressure in elderly women. The analysis of microcirculation by NVC did not reveal structural changes, changes in capillary diameters, or changes in perfusion through FCD in any of the groups. L-arginine increased RBCVmax in all groups except EPS and did not decrease TRBCVmax in EDM2 group. VOP showed improvement in vasoreactivity during reactive hyperemia and after 0.4 mg of sublingual nitroglycerin in all groups except EPS. Conclusion: Oral supplementation with L-arginine (5g/day) for 14 days was effective to improve the vascular/microvascular health of young and elderly women with successful aging and type 2 diabetes mellitus, but insufficient for elderly women with primary sarcopenia