In the teaching of electrocardiography, it is desirable to demonstrate the meaning of the T wave. In the normal human subject it is not easy to produce T wave changes. For this reason any experimental method has considerable value. This paper describes a simple method of demonstrating the effect of delayed and enhanced recovery of the ventricles by the use of a hollow electrode or thermode, which can be cooled or warmed. In use, the thermode is placed in contact with the surface of the left ventricle of an experimental animal. While recording the ECG from the right forelimb and thermode (with the usual conventions, e.g., negativity of thermode produces a downward deflection), the passage of cold water causes the T wave to move downward; then passing warm water through the thermode causes the inverted T wave in sequence to become smaller, isoelectric, then upward.

Transmembrane action potentials were recorded from embryonic rat hearts at ages between 10½ days of gestation and birth (21 to 22 days). The resting potential averaged 30 to 40 mv at 10½ days and increased to around 80 mv by birth. Two periods of rapid increase in resting potential were noted: 1) from 10½ to 13½ days and 2) from 19½ days of gestation to birth. The maximal upstroke velocity of the action potential increased as the resting potential increased. The duration of the ventricular and atrial action potentials was inversely related to heart rate, and their rate sensitivity decreased with age. The atrial action potential lost its rate sensitivity by 13½ days of gestation and the ventricular action potential lost its by birth. At 10½ days diastolic depolarization was found in the area of the ventricle proximate to the A-V junction, the left and right atria, and the sinus venosus. The velocity of the diastolic depolarization was greatestin the sinus venosus and least in the ventricle. The diastolic depolarization decreased with growth and was lost by 13½ days of gestation.

Simultaneous recordings of respirations and instantaneous cardiac frequency by means of a cardiotachometer permit visualization of the sinus arrhythmia due to respiration. Observations made on tracings obtained from 102 patients with a variety of neurologic disorders indicate that the typical respiration-heart rate response may be disturbed by lesions affecting the cardioregulatory mechanisms. Decerebration results in prominent periodic waves of acceleration of the heart rate followed by rebound deceleration. These waves coincide with each deep breath or outburst of periodic breathing. A fixed cardiac frequency is indicative of a complete disconnection between the cardiac pacemaker and the regulatory centers of cardiac activity. Cervical spinal cord transections may cause preponderant bradycardia. It is suggested that simultaneous recordings of the pneumogram and the cardiotachogram may yield useful information regarding the integrity of the regulatory centers of cardiac activity.

The concept of rehabilitation for the completion of total and adequate medical care has not penetrated into the mind of the average doctor as he manages his patient. He is mainly concerned with curative or symptomatic treatment. Much education within the medical profession is needed before rehabilitation as a philosophic concept will make headway.

A clinical laboratory for monitoring a variety of physiological variables has been developed and is described in the following paper. The facility was designed around a system of modular interchangeable functional units. From past experience, the flexibility provided by such a system is essential for efficient operation, because frequently it is necessary to change the physiological event being recorded on short notice during a routine diagnostic run. A detailed description of the various transducers, amplifiers and reproducers is presented.

ArticleSuprasegmental Integration of Cardiac InnervationHebbel E. Hoff, Carlyle G. Breckenridge, and William A. SpencerHebbel E. HoffFrom the Departments of Physiology and Pediatrics, Baylor University College of Medicine and the Southwestern Poliomyelitis Respiratory Center, Houston, Texas, Carlyle G. BreckenridgeFrom the Departments of Physiology and Pediatrics, Baylor University College of Medicine and the Southwestern Poliomyelitis Respiratory Center, Houston, Texas, and William A. SpencerFrom the Departments of Physiology and Pediatrics, Baylor University College of Medicine and the Southwestern Poliomyelitis Respiratory Center, Houston, TexasPublished Online:30 Sep 1952https://doi.org/10.1152/ajplegacy.1952.171.1.178MoreSectionsPDF (2 MB)Download PDF ToolsExport citationAdd to favoritesGet permissionsTrack citations ShareShare onFacebookTwitterLinkedInWeChat Previous Back to Top Next Download PDF FiguresReferencesRelatedInformation Cited ByReferences19 August 2014Central mechanisms of acute ANG II modulation of arterial baroreflex control of renal sympathetic nerve activityMax G. Sanderford, and Vernon S. Bishop1 May 2002 | American Journal of Physiology-Heart and Circulatory Physiology, Vol. 282, No. 5Chronic pain as a reticular formation syndromeThe Pavlovian Journal of Biological Science, Vol. 21, No. 2Use of macroreticular resins for the adsorption of urokinase from human urineBiotechnology Letters, Vol. 7, No. 5Evidence that a GABAergic mechanism at nucleus ambiguus influences reflex-induced vagal activityBrain Research, Vol. 193, No. 2Importance of CNS GABAergic mechanisms in the regulation of cardiovascular functionBrain Research Bulletin, Vol. 5Central Nervous System Control of Baroreceptor Reflexes in the RabbitCirculation Research, Vol. 31, No. 5The Effect of Electric Stimulation of the Brain Stem on the Galvanic Skin ReflexChanges in the tonic activity of the centrifugal fibers of the vagus nerve of cats after decerebrationBulletin of Experimental Biology and Medicine, Vol. 60, No. 6Patterns of sinus arrhythmia in patients with lesions of the central nervous systemThe American Journal of Cardiology, Vol. 16, No. 3Electrocardiographic Alterations Observed During Fractional PneumoencephalographyJournal of Neurosurgery, Vol. 20, No. 4Circulatory disturbances in life-threatening poliomyelitisAmerican Heart Journal, Vol. 59, No. 3FACTORS OF SIGNIFICANCE IN THE RESPIRATORY SYSTEMAnnals of the New York Academy of Sciences, Vol. 66, No. 4Mechanism of the disturbance of cardiac activity on decerebrationBulletin of Experimental Biology and Medicine, Vol. 42, No. 6 More from this issue > Volume 171Issue 1September 1952Pages 178-188 Copyright & PermissionsCopyright © 1952 by American Physiological Societyhttps://doi.org/10.1152/ajplegacy.1952.171.1.178PubMed12985979History Received 19 May 1952 Published online 30 September 1952 Published in print 30 September 1952 Metrics