Altered Metaboreflex Activity In Patients With Metabolic Syndrome

Abstract

In healthy individuals, activation of the muscle metaboreflex leads to increase in mean blood pressure (MBP) due to increase in both systemic vascular resistance (SVR) and cardiac output (CO)1. It has been reported that patients suffering from metabolic syndrome (MS) have a dysregulation of this reflex with an exaggerated SVR increase with respect to normal controls2. However, it is not clear whether this is the consequence of MS per se or this is due to concomitant obesity (OB). PURPOSE: to discover whether MS and OB had different hemodynamic response during the metaboreflex. METHODS: 13 MS patients with obesity (5 females, 50.3±16.3 yrs, body mass index 32.1±4.4), 11 patients with OB without MS (6 females, 38.4±10.1 yrs, body mass index 34.6±5.7) together with 12 control subjects (CTL, 6 females 41±10.5 yrs, body mass index 21.5±2.5) took part in this study. Each individual underwent randomly assigned the following protocol: 1) post-exercise muscle ischemia (PEMI) session, to study the metaboreflex, and 2) control exercise recovery (CER) session. Response to the metaboreflex for each cardiovascular parameter was assessed as PEMI-CER level. Central hemodynamics were evaluated by means of impedance cardiography. RESULTS: the main result was that patients with MS had an exaggerated SVR response with respect to the OB and the CTL group (481.6±595.3, -0.52±376.6, and 130.4±373.7 dynes•s-1•cm-5 for the MS, the OB, and the CTL group respectively, p<0.05), whereas MBP response was not different between groups (10.2±5.6, 8.3±8.6, and 6.05±8.6 mmHg for the MS, the OB, and the CTL group respectively, p>0.05). CONCLUSIONS: This investigation demonstrates that patients with obesity and metabolic syndrome show an exaggerated vasoconstriction in response to metaboreflex activation. This fact was not present in OB without MS. Thus, it is not obesity per se to dysregulate hemodynamics during the metaboreflex. REFERENCES 1 Crisafulli A et al. Muscle metaboreflex-induced increases in stroke volume. Med Sci Sports Exerc 2003; 35: 221-228. 2 Limberg J et al. Mechanical and metabolic reflex activation of the sympathetic nervous system in younger adults with metabolic syndrome. Aut Neurosci 2014 (at press).