Resting membrane potential and Na+,K+-ATPase of rat fast and slow muscles during modeling of hypogravity

Abstract

Antiorthostatic hindlimb suspension (unloading) decreased the resting membrane potential (RMP) of skeletal muscle fibers in fast extensor digitorum longus (EDL) and slow soleus (SOL) muscle of the rat by about 10 % within 7 days and more. Inactivation of the membrane Na+, K+-pump by ouabain brought about similar depolarization as unloading. The increased sodium permeability of the membrane was excluded as the major cause of this depolarization by experiments in which TRIS was substituted for Na+ in the medium. On the other hand, the decrease in the electrogenic participation of the Na+,K+-pump is apparently one of the causes of RMP decrease during hypogravity, in EDL muscle in particular.

Distinct α2 Na,K-ATPase membrane pools are differently involved in early skeletal muscle remodeling during disuse

“…chain expression, changes in ion channel expression, calcium deregulation, cytoskeleton damage, etc. (Shenkman and Nemirovskaya, 2008;Baldwin et al, 2013;Pierno et al, 2013;Ogneva et al, 2014), and a decrease of the RMP (Desaphy et al, 2001;Pierno et al, 2002;Krivoĭ et al, 2008;Tyapkina et al, 2009). The decreased RMP was shown to result from lowered electrogenic Na,K-ATPase activity (Krivoĭ et al, 2008;Tyapkina et al, 2009); specifically, 2 isozyme electrogenic activity decreases after 3 d of HS (Krivoĭ et al, 2008).…”

“…(Shenkman and Nemirovskaya, 2008;Baldwin et al, 2013;Pierno et al, 2013;Ogneva et al, 2014), and a decrease of the RMP (Desaphy et al, 2001;Pierno et al, 2002;Krivoĭ et al, 2008;Tyapkina et al, 2009). The decreased RMP was shown to result from lowered electrogenic Na,K-ATPase activity (Krivoĭ et al, 2008;Tyapkina et al, 2009); specifically, 2 isozyme electrogenic activity decreases after 3 d of HS (Krivoĭ et al, 2008). Short-term (24-72 h) HS alters the Na,K-ATPase of rat soleus muscle in an isoform-specific manner and indicates that 2 Na,K-ATPase alterations precede disuse-induced muscle atrophy (Kravtsova et al, 2015).…”

Metabolic Pathways and Ion Channels Involved in Skeletal Muscle Atrophy: A Starting Point for Potential Therapeutic Strategies

“…Remarkably, muscle workload restores resting potential and Na, K ATPase function [ 125 ]. Accordingly, other studies [ 98 , 122 , 126 , 127 ] show that after 3–7 days of suspension of the limbs, the soleus muscle shows a decrease in the resting membrane potential, deriving from the reduced electrogenic activity of alpha 2 Na, K ATPase. To deepen the mechanism, it has been tested the effect of ouabain at subnanomolar concentrations.…”

How Postural Muscle Senses Disuse? Early Signs and Signals

“…Back in the 1970s, it was discovered that after exposure to real microgravity, a subthreshold decrease in the resting membrane potential (RMP) is observed in rat soleus muscle [for review see 26]. A similar phenomenon is detected in rat soleus muscle during hindlimb unloading of various durations [75][76][77]. In particular, a decrease in RMP was registered after 6 and 12 h of HS [34,78].…”