No effect of anti‐hypertensive treatment during the metaboreflex in patients with essential hypertension

Abstract

In healthy subjects (HS), when the muscle metaboreflex (MM) is activated, the target mean blood pressure (MBP) is reached thanks to cardiac output (CO) increments, whilst systemic vascular resistance (SVR) plays a minor role 1. Differently, in essential hypertension (EHT) hemodynamics during the MM has been often reported to be dys‐regulated, with exaggerated SVR response (i.e. arteriolar vasoconstriction) and reduced CO 2. We tested the hypothesis that standard anti‐hypertensive treatment could improve this abnormal hemodynamics. 20 patients in pharmacological treatment for EHT (10 females; age 54.5±10.4 yrs, time since diagnosis 8.5±6.9 yrs) participated in this study together with a control group of 20 age‐matched HS. At baseline (BAS), they underwent randomly assigned the following protocol to study the MM activity: 1) post‐exercise muscle ischemia (PEMI), and 2) control exercise recovery CER) test. Exercise was dynamic handgrip performed at 30% of the maximum previously assessed. The EHT group performed again the test at least 7 days later (interval 7–15 days) after pharmacological wash‐out (WHT). Response to the MM for each cardiovascular parameter was assessed as PEMI minus CER level. Hemodynamic variables were evaluated by impedance cardiography. Results demonstrated that in EHT, SVR response did not change at the BAS and at the WHT (338.0±452.7 vs. 371.8±465.3 dynes•s‐1•cm‐5 at BAS and at WHT respectively). Moreover, EHT showed higher SVR response than HS (20.9±399.6 dynes•s‐1•cm‐5, p<0.05 vs. both the BAS and the WHT test). However, the MBP response was similar between groups and conditions. Likewise CO was not different between groups. It was concluded that the anti‐hypertensive treatment was not able to counteract the arteriolar vasoconstriction and the increased SVR response experienced by ETH patients during the MM. Further study is warranted to better understand what causes the hemodynamic abnormalities of EHT patients during the MM activation.Support or Funding InformationThis study was supported by the University of Cagliari and the Italian Ministry of Scientific Research.