Effect of chronic K+ deficiency on contractile properties of soleus muscle in rats: evidence of sex differences.
1. Alterations in skeletal muscle function of chronically K(+)-depleted male and female rats were investigated in isolated soleus muscles. 2. By 16 weeks K+ deficiency, plasma K+ concentrations in both male and female rats were reduced to approximately 2 mEq/L, which was accompanied by an approximate 50% reduction in muscle K+ content and a marked increase in muscle Na+ content. These changes were similar in both males and females. 3. Plasma creatine phosphokinase activity progressively increased with time in K(+)-depleted male rats, whereas only a slight increase was observed in female rats. 4. Maximum isometric twitch tension (Pt) and tetanic tension (Po) of K(+)-depleted soleus muscles from male rats was markedly suppressed; this was not seen for soleus muscles obtained from female rats. 5. After exposure to insulin in low-K+ solution, the contractile tension of soleus from the K(+)-depleted male rats was suppressed to a greater extent. 6. All alterations in muscle function during chronic K+ depletion were restored to normal after 2 weeks K+ repletion. 7. The results suggest that there is a preponderance for male over female rats in developing alterations in skeletal muscle function during chronic K+ deficiency. The changes may be associated with abnormalities of muscle membrane permeability and cellular function.
Piyachaturawat
P
P
Department of Physiology, Faculty of Science, Mahidol University, Bangkok, Thailand. Scppy@Mahidol.ac.th
Muchimapura
S
S
Sophasan
S
S
Jariyawat
S
S
Pholpramool
C
C
Satayavivad
J
J
Endou
H
H
D000818:Animals; D003402:Creatine Kinase / Q000097:blood*; D005260:Female; D007328:Insulin / Q000494:pharmacology; D008297:Male; D009119:Muscle Contraction / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology*; D011188:Potassium / Q000008:administration & dosage* / Q000097:blood; D011191:Potassium Deficiency / Q000097:blood*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012737:Sex Factors; D012964:Sodium / Q000737:chemistry
D007328:Insulin; D012964:Sodium; D003402:Creatine Kinase; D011188:Potassium