Changes Of Potassium In Rabbit Skeletal Muscles Caused By Potassium Depletion And The Regulation Mechanisms

Objective: To explore the changes of plasma potassium and skeletal muscle in rabbit during potassium depletion, and discuss the possible regulation mechanisms. Low-K+-content diet was used to make the model of K+ -deficient in rabbit. Plasma potassium were measured to observe the level of potassium depletion, contents of K⁺,Na⁺,Mg²⁺ in skeletal muscle, the activity of Na-K-ATPase on the cell membrane and the changes of Na-K-ATPaseα-isoform were also measured.Methods: Forty-eight healthy male rabbitswere randomly divided into 6 groups(8 foreach group) according to the time of the low-K-content diet. There are normal control group(group A), low-K-content diet for 3 days(group B), 6 days(group C), 9 days(group D), 12 days(group E) and 15 days(group F). Rabbits were kept in animal housing facilities, fed with low-K-content diet, and had free access to distilled water. Rabbits were euthanized in a condition that they are feeding by low-K-content diet till the 15th day as the finish line and keep the corresponding samples.On the day to get the sample, the rabbits were taken to record the weight change and put in a peaceful place. Two hours later, rabbits were anesthetized by intravenous infusion of pentobarbital sodium, soleus muscle and the femoral vein were separated respectively. Blood samples were taken from femoral vein to measure the plasma K level by ion-sensitive electrodes, soleus muscle were taken to survey and evaluate the activity of Na-K-ATPase, contents of K⁺,Na⁺,Mg²⁺ and Na-K-ATPaseα-isoform by corresponding technique.All results are expressed as means±S. Statistical significance among groups was ascertained by one-way ANOVA.Corrected P<0.05 was considered significant. Results:1 There was no significant difference of weight before and after diet.2 Compared with A group,the plasma K were significantly lower in C group(P<0.05).The plasma K goes down with the days of the low-K-content diet feeding increasing.3 Compared with A group,the K⁺ in the soleus muscle began to getting lower after 3 days(P<0.05),Contents of K⁺ in the soleus muscle began to drop down with the days of the low-K-content diet feeding increase.4 Compared with A group,Contents of Na⁺ level in the soleus muscle were significantly higher after 3 days(P<0.05), and as the time went on, contents of Na⁺ in the soleus muscle were getting higher.Compared with A group,the Mg²⁺ level in the soleus muscle were lower after 15 days (P<0.05).5 Compared with A group, the activity of Na,K-ATPase were significantly lower after 3 days(P<0.05), and get even down as the time went on .6 Compared with A group,Na,K-ATPaseα1-isoform in the soleus muscle were lower after 15 days (P<0.05). Theα2-isoform in the soleus muscle went down in group D, and there was significant lower in group F.Conclusion:The low-K-content diet will lead to a shortage of K⁺ in the cell of the soleus muscle, with a significant raise of Na⁺ and decrease of Mg²⁺.The activity of Na,K-ATPase will go down with the plasma K⁺ decreased. Theα1-isoform protein expression of Na-K-ATPase in the soleus muscle have not significant change during the low-K-content diet, while theα2-isoform protein expression get down with the Plasma K⁺ decreased.