FURTHER EXPERIMENTS ON DIRECT AND INDIRECT SCN-CONTRACTURE

Abstract

The strength of the indirect SCN-contracture depends very much upon the time during which the solution containing NaSCN is in contact with the muscle. The indirect contracture is also influenced by changing the composition of the solution containing NaSCN. But in general alterations in the 2nd solution for which the NaSCN solution is exchanged influence the muscle more profoundly. There is a remarkable quanti-tative difference in the susceptibility of muscle to the same ions which seems to be the expression of a more general rule: Ion effects depend to great extent upon the permeability of the cell. There is a close parallelism between KCl-contracture and direct SCN-contracture with respect to the influence of ions, but with the ex-ception that Ba acts upon the KCl-contracture as the other alkali earths do, while it has just the opposite effect upon both direct and indirect NaSCN-contracture. The direct and the indirect SCN-contracture in the tissues of vertebrates can be used to demonstrate the laws of permeability.