Permeability of Muscle to Sodium Ion

Abstract

It is well known that muscles, like blood corpuscles, contain more potassium than sodium, whereas blood plasma contains more sodium than potassium. The unequal distribution of the cations between the corpuscles and the plasma has been shown experimentally 1 and theoretically 2 to be due to the impermeability of the corpuscle membrane to cations. Although a similar explanation may be offered in the case of muscle, no conclusive proof is available. Mauriac, Aubel and Boutiron 3 found that muscle immersed in experimental edema fluid gained Na but lost K, indicating that the muscle membrane is permeable both to Na and K. The permeability of K was confirmed by Wojkczak 4 who found that muscle in nutrient solution containing no glucose lose K. Mond and Amson 5 also found that resting uninjured muscle was permeable to K but impermeable to Na. Callison 6 in a study on the so-called “bound potassium” of muscle found that varying amounts of potassium went into the Ringer solution in which cut pieces of muscle were placed. Thus, while there is general agreement as to the permeability of the muscle to K, the evidence is conflicting with regard to Na. Monauni 7 had reason to believe that even K does not really penetrate through the cells but only through the interstices.

A general criticism which may be raised against all the previous work on the subject is the fact that they are in vitro experiments. In the course of a study on the swelling of muscle we had occasion to test the permeability of muscle in vivo to sodium, and we have obtained results which, we believe, are conclusive.

Rabbits were anesthetized with morphine hydrochloride. The abdominal wall was slit open, the ureters were tied, and the abdominal wall closed. 20 cc. of 25% NaCl solution were injected into the plèural cavity.