William Kaufman

Influence of Temperature on the Electrogram and Monophasic Action Potential of the Mammalian Heart.

Earlier studies in this laboratory demonstrated that warming or cooling portions of the external surface of the ventricles caused characteristic alterations in the T wave of the electrocardiogram. 1 The basis of these T wave changes was found to be alteration in the duration of one or the other of the two components of the electrocardiogram, i. e., of the dextro- or the levocardiogram. Cold prolonged and heat shortened the duration of these components. The following experiments were undertaken to determine the cause of these alterations in the duration of the dextro- and levocardiograms. Electrograms and monophasic action potentials were studied in 5 dogs by the method previously described, 2 one lead being taken from the anterior surface of the right ventricle and the other from the anterior surface of the left ventricle. Negativity at the lead on the right ventricle gave an upward deflection of the beam. The influence of temperature was determined first on the electrogram, and then on the monophasic action potential. Variations in temperature were produced by applying a small tin chamber to the surface of the heart under one or the other electrode, and circulating through the chamber water at 5°C or 55°C. The results of heating or cooling the surface of the heart under one or the other electrode are shown in Fig. 1. When the region under the right ventricle electrode was cooled, an upright end deflection was obtained, while when this region was warmed, the end-deflection was sharply inverted. The duration of the whole electrogram was prolonged when the heart was cooled, and was not materially altered by warming. Exactly opposite effects followed cooling and heating under the electrode on the left ventricle. Cooling produced a prolonged downward end-deflection, while heating produced an upward end-deflection of normal duration.

Some aspects of psychotherapy in allergic practice

The allergists primary goal is to help his patient get well. Frequently this means that he must give his patient not only expert allergic therapy but also expert psychotherapy. A skillful combination of the two will provide the greatest possible benefits to patients suffering not only from allergic illness but also from concomitant emotional disorders.

Vagal Influence on Reflexes of Somatic Musculature.

Johnson and Luckhardt, 1 King, Blair, and Garrey, 2 and Schweitzer and Wright 3 demonstrated that stimulation of the central vagal stumps inhibits reflex activity of the knee jerk and that, in general, this reflex inhibition is independent of secondary circulatory and respiratory changes incident to central vagal stimulation. It was thought desirable to investigate the effects of interrupting the normal vagal afferent stream upon reflex contractions of the tibialis anticus muscle. Dogs anesthetized deeply with morphine and urethane were used as experimental animals. The vago-sympathetic trunks were isolated for cold block. The trachea was directly connected to rebreathing tanks designed to absorb carbon dioxide; oxygen was added as necessary. Respiration was recorded by a spirometer directly connected with the rebreathing tanks. Blood pressure was recorded by a mercury manometer from the right femoral artery. The left sciatic nerve was isolated in the thigh; the hamstring branches cut, the posterior tibial nerve identified, severed, and the central end placed on shielded electrodes of special design. The electrodes were connected to the secondary coil of an inductorium whose primary received the discharge from a Thyraton stimulator. After the left leg was immobilized, the tendon of the tibialis anticus muscle was freed for a distance of about 6 cm above its insertion and connected to an isotonic spring tension myograph. A slight constant tension was exerted on the muscle throughout the experiment. The vagi were cold blocked and recordable reflex contractions were elicited from the tibialis anticus muscle at a constant rate (40 to 60 stimuli per minute). Upon deblocking the vagi, the reflex amplitude gradually decreased to zero, indicating inhibition of the tibialis anticus reflex; upon blocking of the vagi, the reflex contractions of the tibialis anticus muscle gradually reappeared.