A Bipolar Theory of Living Processes

“Tetanus, up to 25 secs., of a live nerve, does not cause a change of temperature (other than at the seat of excitation) of more than about + 6 10-5 ° ©. There is no evidence of any change at all, but the method does not allow conclusions beyond this limit. Кот every single propagated disturbance, the change of temperature, therefore, cannot exceed about 10-8 ° C., a hundred millionth of a degree. This corresponds to an oxidative process in which only one molecule of oxygen is used in a space of visible size, viz.,—a 3u cube. This suggests very strongly, though of course it does not finally prove, that the propagated nervous impulse is not a wave of irreversible chemical breakdown, but a reversible change of a purely physical nature.”

А thorough search of the literature, however, has discovered no reference to the measurement of variations in the temperature of the brain and other internal organs under diverse conditions with the exception of the work of the investigators cited above, that of Stengel and Hopkins (12) on the intragastrie temperature and the work of Macleod and Taylor (13) on the effects of hot and cold applications on the superficial and deep temperatures. By the invitation of Dr. E. P. Hyde and with the active cooperation of Dr. W. E. Forsythe, our initial experiments were performed at the Nela Research Laboratory. А copper-constantan thermocouple, the wires passed through a glass tube in the end of which the couple was sealed, was used, the “cold” junction being placed in melting ice in a thermos bottle.

Three rabbits were used and as the purpose of this test was only to determine the feasibility of proceeding further, a series of rapid tests was made with most gratifying and encouraging results. This preliminary experiment proved: 1. That it is possible to insert a thermocouple directly into the brain, the liver, the muscle, the pleural cavity, for a prolonged period without any notable effect upon the general condition of the animal. 2. That practically any alteration in the condition of the animal —light and deep anesthesia, struggling, shock-producing manipulations, etc.—is accompanied by a measurable change in the temperature of the brain.

3. That the temperature of the brain decreases progressively under ether anesthesia. 4. That the injection of adrenalin produces a characteristic rise and fall in the temperature of the brain closely related to the clinical phenomena—a finding of extreme significance in view of our later studies. These curves were not plotted, nor was any attempt made to translate the galvanometer readings into actual temperature variations, but the purpose of this preliminary experiment having been attained, we proceeded to devise the essential apparatus for an extensive investigation. We wish at this point again to express our appreciation to Doctor Hyde and Doctor Forsythe for their interest and active cooperation in securing this first evidence.

Apparatus: The essential apparatus consisted of Leeds and Northrup galvanometers of types R and H with especially constructed copper-constantan thermocouples made of 5 mil wire twisted together and soldered. The recording junction was exposed, the leads being separated from each other and protected by concentric glass tubes, the ends of which were joined by dental cement. The junction was kept as small as possible and the protecting glass tubes were of the:smallest possible caliber. These tubes were bent into such shapes as could be most easily and firmly secured in the tissue for which each was designed. This is a vitally important point, as closeness and constancy of contact of the thermo-junction with the tissue under examination is essential to the attainment of dependable records.

The use of any metal in the construction of the thermocouples was avoided, for fear it might conduct the heat away from the area of insertion and lead to local cooling. This is an essential precaution in working with an instrument so sensitive to small temperature changes; moreover, it is very important to remove any material which would produce a lag in the response of the indieating instrument to the local changes of temperature. The “cold” or constant junction of the thermocouple was immersed in a tube of oil suspended in a constant temperature bath, the temperature of which was maintained at 39? C., thus bringing the whole range of temperature in the tissues studied upon the

scale of the galvanometers. As the extreme range of temperatures involved in living rabbit tissues do not exceed 7° C., it is possible to measure variations by the direct deflections of a galvanometer of suitable sensitivity. The circuit was of very low resistance with all wire connections soldered and symmetrical, and with all contacts non-frictional and of low resistance. The galvanometers were short-circuited when not in use and were protected from extreme deviations.

Calibrations were made immediately after the measurements to which they applied, as there is always a tendency for the instruments to drift from day to day. The calibrations were made by immersing the active junctions along with a standard thermometer in water in a thermos bottle. То avoid error due to the lag in the response of the large bulk of mercury in the standard mercury thermometer, the readings were always made on a falling temperature, as the decrease was so gradual as to minimize error. With this apparatus, temperature variations could be measured to within

Technic: As far as possible in each group of experiments rabbits of approximately equal size and age were used. This point was not as essential, however, as in our conductivity studies—as in these experiments each animal acted as its own control. A small hole through the skull over the cortex at the right of the median ridge was made by an especially constructed trephine, the size of the hole being just large enough to admit the glass tube containing the thermo-junction. This tube was bent at an angle, one irm of which was just long enough to enter the brain to a depth of approximately one-third to one-half a centimeter, the other lying along the top of the head. Absorbent cotton was placed over this to eliminate the chance of chilling, the whole being firmly secured in place by strips of adhesive. By this means the thermojunction was held securely in place even when the animal moved violently.

It was more difficult to secure an immovable junction in the liver, but in most instances this was accomplished by inserting one arm of a right-angled tube through a small opening just below the ribs, and securing it by metal clips through the muscle, with adhesive strips over the skin. By bending the tubes at a right or slightly acute angle, and the use of clips and abundant adhesive, constant contact could usually be secured in any tissue, and by the free use of cotton, complete protection from external chilling was assured.

this precluded the possibility of simultaneous readings of the variations in temperature in different organs, another galvanometer was installed. Thus, two observers could make synchronous readings at 15-second intervals or less. Seventy-seven rabbits were used in these preliminary studies, consistent records being secured in sixty-three. Any experiment was discarded if at the termination of the experiment any fault in contact was found, the insertion of the thermo-junction being examined at the conclusion of every experiment. As noted above, calibration at the conclusion of each group of experiments and repeated testing of the constant temperature checked the findings throughout.

In these preliminary studies, the effects of various agents and procedures has been observed, the temperature variations in the brain being measured in every instance, in the liver in most of the animals, and in the muscle and thyroid each in two instances. In the first experiments, as noted above, the galvanometer readings were recorded at 30-second intervals, readings being made alternately when more than one thermocouple was employed. Later by the use of two galvanometers and two observers simultaneous readings were made at 15-second intervals.

Fifteen-second intervals, however, are not sufficiently short to assure the recording of every variation in the temperature of the brain. Frequently a rapid deviation of the galvanometer was observed between the recorded readings, but to assure the greatest possible accuracy by the undivided attention of the observers to the 15-second readings, they were told to allow no other observation to interfere with the correct recording of these—an important injunction in experiments which in many instances were 11% to 2 hours or more in length, requiring the accurate reading and recording of 300 and more galvanometer readings by each observer. It early became apparent that a method of continuous record is required to register all the temperature changes in the infinitely sensitive brain, for the slightest stimulation of the animal under observation—by the sound of a closing door, a motion of the hand before the eyes, a light touch, ete.—produced a measurable, if but slight and brief, alteration in the brain temperature. In many instances an abrupt rise was observed immediately prior to a struggle which was marked by a sharp fall. This was observed so often that when in a quiet animal the temperature of the brain rose abruptly, a struggle was expected.

The variation in the temperature of the brain which preceded and accompanied a struggle oceurred in such rapid succession that it was impossible in every instance to synchronize the event and _ the galvanometer reading with certainty. The apparent variations in the nature of the response to certain stimuli are undoubtedly due to this difficulty which can only be obviated by continuous records. Tn many cases various forms of stimulation were applied to the same animal. In the following presentations, therefore, instead of following the usual method of presentation of protocols, the findings will be summarized according to the various forms of stimula-

tion employed. | . Especial appreciation is due to Donald D. Forward for his efficient coóperation in many details of this research and to George Harris Crile for his patient and accurate readings of the galvanometer. 1. By the use of especially constructed thermocouples it is possible to measure temperature variations in living tissues to within 2. By the described apparatus and technic the progress of functional changes in the brain and other tissues in stimulation and exhaustion from various causes has been observed, and the findings correlated with the histologic changes and the alterations in electric conductivity established by previous researches.

1. Свих. A Physical Interpretation of Shock, Exhaustion and Restoration, London, 1921. Expérimental de PÉlectricité et du Magnétisme, Paris, 1835, iv, 159. By GEORGE W. ORILE AND Amy Е. ROWLAND From the American Jowrnal of Physiology, Vol. 62, No. 2, October, 1922 Under the methods described in the preceding section of this report, animals were subjected to stimulation and exhaustion from various agents and the temperature variations produced by each were observed and recorded.

1. Inhalation anesthesia. Inhalation anesthesia—ether or nitrous oxid—produced a continuously progressive decrease in the temperature of the brain and the liver, this decrease being much greater in the case of ether. In the course of prolonged ether anesthesia the temperature of the brain and of the liver may decrease from 11% to 2° or the decrease may amount even to 4°; while under even prolonged nitrous oxid oxygen anesthesia, the decrease in temperature, though progressive, is so slight as to be practically negligible. The initial stage (stage of excitement) both of ether and nitrous oxid anesthesia is marked by a slight increase in the temperature of the brain. ‘This initial increase in temperature corresponds to the hyperchromatic stage described in our histologic studies of the brain cells and to the increased electric conductivity of the brain which we found was present in the first stage of both ether and nitrous oxid anesthesia.

3. Electrical stimulation. In this group of experiments the eurrent from a single dry cell attached to an induction coil was used, the coil being so adjusted as to produce a sharp tingling of the tongue with the terminals about 0.5 cm. apart. The terminal wires were applied directly to the sciatic nerve, the sciatic nerves on both sides being exposed. On each side stimulation was applied first to the unblocked nerve which was then novocainized and the eurrent again applied. The animals were under ether anesthesia throughout.

Stimulation of the unblocked nerve produced a change in the temperature of both the brain and the liver in opposite directions. In certain cases the first stimulation produced an increase in the temperature of the brain and a decrease in the temperature of the liver; while the like stimulation of the opposite nerve produced a decrease in the temperature of the brain and an increase in the temperature of the liver, these opposite effects being especially marked when the first response had been particularly severe. After complete blocking of the nerve there was but slight or no response to stimulation of the sciatic nerve.

3. Abdominal trauma, exposure of viscera, etc. Every injury of the abdominal wall or shock-producing manipulation of the peritoneum or intestine was registered by an alteration in the temperature of the brain. These variations were especially manifested during the manipulations essential to excision of the adrenals or to ligation of the liver. Exposure of the viscera produced a precipitate decrease in the temperature of the brain. The like fall in the temperature in the liver which in part may be attributed to the direct exposure, may in part be due to other causes.

Hot water in stomach: The introduction of hot water into the stomach through a stomach tube increased the temperature of the brain and the liver, the increase in the temperature of the brain occurring first. In some instances, the temperature of the liver did not begin to increase until a minute or more after the beginning of the increase in the brain was noted. 4. Excision of organs. Hepatectomy was followed by a continually progressive fall in the temperature of the brain which was unchecked by any therapeutic measure. The rapidity of the | decrease, however, varied according to the condition of the animal and the amount of trauma produced by ligation of the liver.

Adrenalectomy produced a rapid decrease in the temperature of the brain, although the short duration of life in two of the three animals in which adrenalectomy was done makes it impossible to determine to what degree this decrease was due to the trauma of the operation. 5. Acid. In one experiment the intravenous injection of hydrochloric acid (1 ce. of 10 per cent solution) was immediately followed by an abrupt rise in the temperature of the brain amounting to 0.7° C. with an equally abrupt fall to 0.56? C. below the point at which the acid was injected; from this point there was a rapid and precipitous decline until death which occurred 5 minutes after the injection. 'The liver showed no response to the acid injection and at the time of death the temperature of the liver was but 0.46? C. below the point at which the acid was injected, while the total decline in the temperature of the brain amounted to 1.63? C.

6. Alkalt. In one experiment 8 cc. of a saturated solution of sodium bicarbonate were injected intravenously. During the injection, which lasted 4 minutes, the temperature of the brain rose 0.5? C. There followed a fall to a point 0.5? below the point at which the injection was started, this period lasting for 8 minutes. During the following 10 minutes there was a further gradual decrease of 0.339. Ether was then given, the abdomen opened, viscera exposed and extreme shock EU Em manipulations were made. Although the fall in brain temperature was accelerated thereby the picture does not correspond to that produced by like exposure and trauma in other experiments. Тһе animal lived for 15 minutes after the abdomen was closed, and was finally sacrificed when the temperature of the brain had reached the low point of 34? C. As after the injection of hydrochlorie acid, the liver showed no response to the injection of sodium bicarbonate, its temperature declining but slowly until the viscera were exposed.

7. Strychnin. The effects of strychnin injection upon the tom: perature of the brain varied in relation to the clinical effects. Ја an animal in which typical convulsions occurred there were correspondingly great variations in the brain temperature; while in another in which the muscular contractions were less marked the variations in the temperature of the brain were correspondingly less than in the former instance. In no instance was the temperature of the liver affected by the injection of strychnin.

In two animals under nitrous oxid anesthesia the injection of strychnin produced but a slight variation in the brain temperature, although in one of these there were strong convulsions. 8. Diphtheria toxin. The temperature of the brain and liver was watched continuously for hours after the injection of diphtheria toxin. No significant change in the liver was noted but there were variations in the temperature of the brain. In one instance, on the day after the injection of the toxin, the animal was placed under ether anesthesia when the brain showed a precipitate decline in temperature, death occurring 21 minutes after the anesthesia was started. The rectal temperature when the toxin was injected was 38.5? С. At 8:00 o'clock on the following morning it was 41.1?, and 234 hours later it had fallen to 40.8°. Hight minutes before death it was 38.8°.

1. The progress of exhaustion from any cause—-continuous ether anesthesia, adrenalectomy, physical trauma—is marked by a progressive decrease in the temperature of the brain and the liver, the rapidity of which bears a direct relation to the rate at which the degree of exhaustion advances. 2. The stage of excitement of ether and of nitrous oxid anesthesia is marked by an increase in the temperature of the brain. 3. After hepatectomy the temperature of the brain declines progressively until death, the resultant curve corresponding closely to that produced by continuous ether anesthesia.

4. Muscular activity, either voluntary or produced by direct electric stimulation of a nerve, is accompanied by rapid alterations in the temperature of the brain and the liver corresponding to the phases of the muscular activity—these alterations, however, being in opposite directions. 5. No alteration in the temperature of the liver appears to be produced by the injection of strychnin, of an acid or of an alkali, although marked and characteristic changes, corresponding in each ease to the clinical phenomena, are produced by each in the temperature of the brain.

6. Exposure of the viscera and abdominal trauma alike produce a rapid fall in the temperature of the brain and the liver, the change in the latter being in part but not entirely accounted for by the direct chilling of the liver substance. 7. The restorative effect of the introduction of hot water into the stomach is marked by an immediate elevation of the temperature of the brain which measurably precedes—in some instances by a minute or more—the resultant elevation in the temperature of the liver.

8. The Jowered resistance to inhalation anesthesia produced by an acute infection is illustrated by the rapid decline in the temperature of the brain of an animal subjected to ether anesthesia 24 hours after an intravenous injection of diphtheria toxin. In section II of this presentation, we have reported a series of studies of the effects of various agents upon the temperature of the brain and the liver as indicated by measurements by means of especially devised thermocouples.

Early in the progress of these studies it became evident that the response of the brain to the injection of adrenalin was so uniformly manifested in normal animals by typical temperature changes that we adopted the temperature response of the brain to adrenalin as a kind of unit of comparison in a series of experiments, the findings in which appear to be so significant that we make them the subject of a separate report. Four-tenths of a cubie centimeter per kgm. of 1:1000 Parke, Davis & Co.’s adrenalin was the dose employed throughout these experiments after a series of tests had shown that this dosage gave the most uniform response in normal rabbits.