Über den tatsächlichen Orthophosphat- und N-Phosphorylkreatingehalt des Säugetierherzens

Summary

1. Cardiac ventricular muscle of adult, anesthetized, open-chest dogs, guinea pigs, and rabbits given artificial respiration was compressed by means of a pair of −190°C cold aluminum tongs in situ in 0.02–0.4 seconds to frozen plates 0.4–1.5 mm in thickness.

2. Determinations of phosphates extracted from the finely powdered plates with 0° or −35°C cold perchloric acid yielded, among other results, the following values per gram of dog, guinea pig, and rabbit myocardium, respectively: 1.9, 2.0, and 1.9 μmoles of orthophosphate; and 12.8, 10.9, and 8.2 μmoles of N-phosphorylcreatine (“labile” phosphate). “Bound” creatine, analyzed in extracts of guinea pig and rabbit hearts, corresponded quantitatively to the labile phosphate.

3. Cardiac muscle samples which were excised and immediately immersed in liquid air contained 3–4 times as much orthophosphate and only a little more than half as much phosphorylcreatine as the metal-cooled tissue. There was also less total acid-soluble phosphate present. The sum of orthophosphate and phosphorylcreatine and the amounts of “10-minute”-phosphate and of total creatine were not significantly altered by excision and freezing in liquid air.

4. The rapidly beating hearts contained per gram (a) less orthophosphate than is found in the resting skeletal musculature; and (b) as much as or more phosphorylcreatine than there exists, according to data in the literature, in certain types of skeletal muscle in the resting state.

5. The problem of obtaining a warm-blooded heart, or a part of it, for analysis without inducing changes in chemical composition is considered in relation to the anatomy of the organ. The advantage is noted which the cooling tongs technique affords in this regard over other methods of tissue freezing.