Oxygen Consumption of the Cardiac Ganglion of Limulus Polyphemus. ∗

Abstract

The CO₂ production of the cardiac ganglion of Limulus has been studied by Garrey, 1 who found a direct quantitative relation between the rate of the heart beat and the rate of CO₂ formation in the ganglion. Both of these rates were augmented when the ganglion was stimulated chemically, mechanically, or electrically, and diminished when the inhibitory nerves were stimulated.

The object of our experiments was to study the oxygen consumption of the ganglion during rest and during electrical stimulation. The method employed was the Warburg manometric technique. 2 For stimulation experiments we used chambers with simple manometers and platinum electrodes sealed in, as employed by Gerard. 3 The ganglia were kept in sea water instead of Ringer's solution. At least 5 ganglia, having a combined moist weight of about 0.1 gm., were used. After careful dissection they were kept cold until mounted on the electrodes, after which the experiment was conducted at a temperature of 24.6 to 24.8°C.

Readings were taken every 10 or 15 minutes for a period of about 3 1/2 hours. After a resting period of one-half to one hour, stimulation was applied for 10 minutes at the rate of 2 shocks (one make and one break) per second by means of a Harvard inductorium with coil set at about 4 cm. and one dry cell. Another resting period of about 40 minutes was allowed to elapse before the next stimulation was given, and this procedure was repeated several times. At the end of the experiment the dry weight of the ganglia was obtained, and from this the moist weight was calculated on the basis of 80% water.

The table shows results obtained in 3 experiments when stimulation was given. The average resting value for these 3 experiments was 104 cu, mm. of oxygen per gm. of moist weight per hour, with variations between 93 and 120 cu. mm., while the average obtained in 9 experiments was 114 cu. mm., with variations between 30 and 217.