RESEARCHES ON THE PERFUSED HEART: THE EFFECTS OF INORGANIC SALTS

Abstract

It is shown that many substances may produce heart block if they be perfused through the heart at a too high pressure.The salts of potassium may be divided into two groups with reference to their action on the heart of the frog. This division is determined by the presence or absence of a “contraction effect,” when the salts are employed in high concentration. The absence of this “contraction effect” with the one group of salts is shown to be due to their action on some of the calcium salts of cardiac muscle. All the salts temporarily abolish the rhythmical activity of the heart.The division of the salts into these two groups is in accord with their action on the sartorius muscle.Potassium salts give rise to two types of contraction in the cardiac muscle of the frog, viz., the “tonic contraction” and the “contraction effect.” The former could be produced by all the salts of potassium examined, and seemed to be in some way associated with the rhythmical contraction process; the latter was the determining factor for dividing the salts into two groups, and could be produced in the non‐beating heart.There is a seasonal, and also individual, difference in the action of a 0·225 per cent. solution of potassium chloride on the frog's heart. In any heart, and at any season, the seasonal differences found in the fresh heart may be reversed or paralleled by appropriate treatment with calcium or potassium salts. The conclusion is drawn that there are seasonal variations in the balance between the calcium and potassium salts in the heart muscle of the frog. It is possible that temperature may be a factor in bringing about such changes.There are at least three groups of calcium salts in the cardiac muscle of the frog.The salts of one of these groups seem only to be displaced by such potassium salts as the oxalate and citrate. The results obtained after such displacement suggest that these salts are normally concerned in bringing about some limitation of the direct action of potassium salts on heart muscle.The other calcium salts are readily displaced by all potassium salts. Such displacement is followed by derangement of spontaneous contractions and of rhythm, such as to suggest the loss of some form of governing or controlling influence. Since restoration to the normal depends on calcium salts, these would appear to keep the cardiac functions in check in addition to being essential to their initiation. Irregularities of rhythm and contraction may appear independently of each other, and for this reason the calcium salts governing these processes are divided into two separate groups. The calcium salts controlling rhythm also appear to mediate the action of the vagus nerve on the heart.In conclusion, I wish to express my sincere thanks to Professor Gotch for his valuable criticism and advice.