Sodium regulation with periodic fluid redistribution during diminished muscular activity in healthy subjects

Yury Feofil Federenko; Yury Nikita Yaroshenko; Pavel Leonid Merkov; Sergei Kirill Deno gratov

Yury Feofil Federenko Department Biochemistry, Institute of Hypokinetic Physiology, Athens, Greece
Yury Nikita Yaroshenko Department Biochemistry, Institute of Hypokinetic Physiology, Athens, Greece
Pavel Leonid Merkov Department Biochemistry, Institute of Hypokinetic Physiology, Athens, Greece
Sergei Kirill Deno gratov Department Biochemistry, Institute of Hypokinetic Physiology, Athens, Greece

Keywords: Hypokinesia, Muscle sodium, Periodic head down tilt, Sodium losses, Sodium repletion, Vascular volume

Abstract

Background and Aim: Mineral loss is an established reaction to diminished muscular activity (Hypokinesia; HK). It has been assumed that periodic fluid redistribution (PFR) contributes to vascular volume. Fluid volume expansion could affect electrolyte metabolism. We hypothesized that chronic PFR may contribute to or improve electrolyte regulation during diminished activity. Therefore, we studied the potential benefits of sodium (Na⁺) regulation with chronic PFR during HK. Methods: The study was conducted on 40 male subjects for the duration of 390‑days preexperimental period and a 364‑days experimental period. They were equally divided into four‑groups: Active control subjects (ACS), hypokinetic subjects (HKS), periodic fluid redistribution control subjects (PFRCS), and periodic fluid redistribution hypokinetic subjects (PFRHS). Results: Muscle Na⁺ increased (P < 0.05) and plasma Na⁺ and Na⁺ losses decreased (P < 0.05) in the PFRHS group compared with the HKS group. Muscle Na⁺ decreased (P < 0.05) and plasma Na⁺ and Na⁺ losses increased (P < 0.05) in the HKS group compared with the preexperimental period levels and the values of the other groups. Muscle Na⁺, plasma Na⁺ and Na⁺ losses were benefited much less in the PFRCS group than in the PFRHS group. Muscle Na⁺, plasma Na⁺ and Na⁺ losses were not affected in the ACS group compared with their preexperimental values. Conclusion: The current study shows that muscle Na⁺ increases and Na⁺ losses decreases with chronic PFR suggesting the potential benefits of Na⁺ regulation during diminished activity.