Experimental Studies of the Electrocardiographic Effect of Potassium Solution on a Toad's Heart in the Presence of Insulin and Glucose

• Published in: The Tohoku Journal of Experimental Medicine Vol. 74; no. 1; pp. 43 - 57
• Main Authors: Nakamura, Takashi, Kanazawa, Tomohiro, Takahashi, Nobumitsu
• Format: Journal Article
• Language: English
• Published: Japan Tohoku University Medical Press 01.01.1961
• Subjects: Electrocardiography - pharmacology; Glucose - pharmacology; Heart; Humans; Insulin - pharmacology; Old Medline; Potassium - pharmacology; POTASSIUM/pharmacology; ELECTROCARDIOGRAPHY/pharmacology; GLUCOSE/pharmacology; INSULIN/pharmacology
• ISSN: 0040-8727; 1349-3329
• DOI: 10.1620/tjem.74.43

1) To examine the effect of insulin on the myocardial electrolytes the isolated heart of a toad was immersed in the insulin-glucose-Ringer's solution, and potassium and sodium contents of the solution were determined with time by use of a flamephotometory. Potassium content decreased with time. As to sodium, however, no uniform change was observed. This finding shows that the heart took up potassium from the surrounding solution in the presence of insulin and glucose. 2) Another study was performed on the electrocardiographic effect of potassium solution on a heart treated with insulin and glucose. The ventricular surface of a toad was applied continuously with the insulin-glucose-Ringer's solution, the heart was covered with potassium solutions of various concentrations, and the direct unipolar electrocardiogram was taken. 3) Immediately and soon after the administration of the insulin-glucose-Ringer's solution, the ST-elevation was obtained by 6-7 mEq/L potassium solution, which always produces it in the normal intact heart. As time passed, the ST-elevation was not produced by 6-7 mEq/L potassium solution. It was necessary to use samples of higher concentration in order to produce the ST-elevation as the course progressed. After the cessation of the insulin-glucose-Ringer's solution, the threshold value of potassium concentration to produce the ST-elevation returned gradually to the previous normal level. 4) These findings may be explained by the supposition that the intracellular potassium is gradually increased after the administration of the insulin-Ringer's solution and is decreasing after the cessation. In the case of the increased myocardial potassium, the ratio of intra- to extracellular potassium plays an important role in the ST-deviation. 5) When the threshold value rose, the ST-depression was noted immediately if the normal Ringer's solution was used. This electrocardiographic finding may be taken for an electrocardiogram of the increased myocardial potassium when the external is normal.