RESEARCHES ON THE PERFUSED HEART: ANÆSTHETICS AND INORGANIC SALTS

Three modes of contraction are described as produced by the anæsthetics in the frog's ventricle. The actions of the anæsthetics are also found capable of classification as reversible and irreversible. Many of these reversible actions are influenced by the salts of calcium and potassium. Thus, the action of the anæsthetics in depressing the beats of the heart to a constant level by a lessening of systole is antagonised by calcium salts, and the same salts are necessary for subsequent restoration of the beats to their original size. Similarly, calcium salts are found necessary for restoration of initiation and propagation when these processes were depressed by the anæsthetics. The action of each of the substances examined in stopping the heart in the contracted condition was resolved into the processes of stopping the heart in the dilated condition and production of contraction. An increased amplitude of contraction resulted from the action of the anæsthetics after they had undoubtedly done some form of damage to the heart. Reasons are given for believing this damage to be primarily associated with the sarcoplasm, the results being in agreement with others obtained by the author that the sarcoplasm is a structure which governs the amplitude of contraction in virtue of its content in calcium. It is suggested that in strengths sufficient to produce anæsthesia these anæsthetics bring about a reduction in the effective concentration of the calcium salts and phosphates in the tissues, and that, consequent on such reduction, those functions dependent on calcium will be affected, e.g. initiation, conduction, excitability, oxidation, etc.