Abstract
This investigation was undertaken in an attempt to determine the effect of ultra violet on tissue subjected to potassium excess. For this purpose the heart of the clam, Venus mercenaria, was used.
Records were obtained of the ventricular beat of the heart in situ. A small hook, made of glass capillary tubing, was inserted into the apex of the ventricle and, by means of a thread attached to the hook and a light balanced lever (a drinking straw), records were obtained on a moving kymograph. The clam, on the half shell, was placed in a finger bowl which was filled with sea water. To this the desired amount of potassium chloride was added.
The ultra violet source was a Cooper-Hewitt Uviarc (6-inch tube with reflector and running at 110 volts D. C.) placed at 35 cm. from the preparation. A thermopile, with a blackened couple, at the heart, served as a temperature index. The sensitivity of the galvanometer enabled temperature changes of 0.01°C. to be observed. During all of the experiments the temperature changes were negligible. Room temperature varied from 22 to 27°C. During the course of an experiment the temperature both of the room and of the heart never changed more than one degree Centigrade from the beginning of the experiment to the end. Temperature rise during irradiation never exceeded 0.3°C.
Short ultra violet irradiation (2-3 min.) of the clam heart appears to cause a marked increase in tonus, a definite decrease in amplitude, but does not affect the pace maker.
Experiments were per formed with potassium chloride concentrations up to 2.7% in sea water. When concentrations above 1.36% potassium chloride were used ultra violet (1-2 min.) did not always restore a rhythm.
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