Study of potassium deficiency in cardiac muscle: quantitative X-ray microanalysis and cryotechniques.

An imbalance of potassium in cardiac muscle causes an alteration of heart function. The distribution and concentration of potassium in rat papillary heart muscle was studied using cryofixation and X-ray microanalysis. Freeze-dried cryosections and sections of freeze-dried, embedded tissue were analysed. Bulk frozen specimens were freeze-dried either in a vacuum or by a new technique using liquid propane as a cryodehydration medium. These two methods of freeze-drying were tested for elemental retention in other specimens, with comparable results. A potassium concentration of 120 mmol/l was measured in normal myocytes of cardiac papillary muscle compared to 80 mmol/l in myocytes of animals stressed by a temperature of 45 degrees C for 1 h. The presumed physiological significance of the findings is discussed.