Increased muscle potassium from head down tilt sleeping of healthy subjects during diminished muscular activity

Abstract

Background and Aim: Periodic fluid redistribution (PFR) with head down tilt (HDT) sleeping produces less fluid loss and more fluid volume. We hypothesized that chronic PFR with HDT sleeping would contribute to and improve electrolyte regulation. Therefore, we studied the potential of regulation of muscle potassium (K+) and K+ losses with chronic PFR of HDT sleeping during diminished muscular activity (hypokinesia). Methods: Studies were conducted on 40 male healthy volunteers. They were equally divided into four groups: Active control subjects (ACS), hypokinetic subjects (HKS), HDT sleeping control subjects (HDTSCS), and HDT sleeping hypokinetic subjects (HDTSHS). Results: Muscle K+ increased (P < 0.05) and plasma K+ and K+ losses decreased (P < 0.05) in the HDTSHS group compared to HKS group. In the HKS group, muscle K+ reduced (P < 0.05) and plasma K+ and K+ losses increased (P < 0.05) compared to preexperimental levels and the values of the other groups. In the HDTSCS group, muscle K+, plasma K+, and K+ losses were affected much less than in the HDTSHS group. Muscle K+, plasma K+, and K+ losses did not change in the ACS group compared to their preexperimental values. Conclusion: The current study shows that muscle K+ muscular increases and K+ losses decrease with chronic PFR of HDT sleeping suggesting regulation of K+ deposition during diminished activity.