Cation concentration change in rat skeletal muscles associated with potassium deficiency and denervation.

CONWAY and HINGERTY1) showed that feeding of rats with K-free diet produced high Na and low K contents in muscle, the K loss being greater than the Na gain during a short time of K-deficiency, but that a further decrease in K content by feeding of K-free diets from 4 to 26 days was compensated by an equivalent gain of Na. COOKE et al.2) demonstrated also in the rat skeletal muscle made K-deficient for 3 weeks that an increase in the intracellular sodium concentration, •kNa•li, amounted approximately to twothirds of a decrease in the intracellular potassium concentration, •kK•li, and that the ionic content was restored to the normal value by application of K-salt to K-deficient rats. Somewhat similar movement of Na and K in the rat muscle was observed by MUNTWYLER and GRIFFIN3) during development of K-deficiency and during the recovery from it. In addition, these studies showed that change in plasma K in K-deficient rats was related closely to K loss and Na gain in muscles, although the results are not extensive enough to reveal successive changes in the electrolyte composition of plasma or muscles during the course of K-depletion. On the other hand, DRAHOTA and GUTMANN4) reported that the K content of chronically denervated extensor digitorum longus muscle (EDL) resembled an innervated soleus muscle (SOL). An increase of •kNa•li and a decrease of CKJi in both SOL and EDL have also been observed by KIYOHARA and KOBAYASHI5) following denervation of muscles, and the cation content of denervated EDLs resemble that of SOLs. Similar findings were reported on both human and animals with muscular dystrophy6-8). Therefore, the object of the present investigation was first to examine changes in the ionic composition of the plasma and muscles of rats during K-deficiency, secondly to learn whether or not •kNa•li and •kK•li in chronically