The respiratory heart rate relationship was examined in 10 decerebrate cats. The relationship appears to be a multi-part phenomenon consisting of (1) the inspiratory acceleration of the heart rate, which is well known, plus (2) the tendency toward small numbered relationships of integers between heart and respiration, as for example 2:1 to 5:1 heart rate to respiratory rate rather than complete randomness in the multiples of cardiac intervals in the respiratory cycle, and (3) registry of the heart and respiratory cycles upon each other in conformity to definitions of linear autonomous systems. So the phenomenon can be attributable to the influence of respiration upon the heart, the influence of the heart upon respiration, resulting in the mutual influence of both in supplying the physiological needs of perfusion of the periphery revealing higher integrations which an autonomous system would require.

Acutely decerebrate (midcollicular) cats do not, or rarely if ever, walk spontaneously; nor do they show phasic movements of progression. After low thoracic cordotomy in a Schiff-Sherrington preparation with enhanced forelimb rigidity, approximately 50% of the preparations begin to show spontaneous locomotory movements in the forelimbs. In some cases these movements are in periodic bursts, and at these times are associated with waxing hyperpnea beginning before the onset of the forelimb movements. This indicates the presence of an intrinsic exercise hyperpnea mechanism mediated within the central nervous system in centers caudal to the hypothalamus.

A transient time-dependent increase in tidal volume (TV) and respiratory rate has been observed as a spirometric loading effect in experiments on 22 decerebrate cats. Respiration was recorded via the impedance pneumograph throughout the entire experiment while tidal volume was measured at intervals of 10-60 min on a spirometer. A total of 233 spirograms was recorded. The mean control tidal volume was 14 ml/kg, followed by an average increase of 30%, 43%, 51%, and 64% at 30, 60, 90, and 120 sec on the spirometer respectively. Spirometric respiratory rate also increased and as a result instantaneous minute volumes (MV) showed increases up to nearly 400% of control. Maximal effects occurred within 80 sec reflecting a sequential combination of reflex (via vagal afferents) and chemical (increased CO2) factors reaching a new equilibrium. We also noted a spirometric regularization of previously irregular or periodic (Biot's) breathing. It is apparent that the spirometer introduces small and graded perturbations into respiratory control systems.

Single-pulse stimulation of the vagus nerve in turtles ( Pseudymys floridana ) produced the well-known negative inotropic effect on the atria. After stimulation, the peak amplitudes of the atrial contractions exhibited an envelope which appeared to be proportional to the concentration of acetylcholine at the receptor sites. Postulating a quantized release of acetylcholine with each stimulus, the envelope was modeled by a two-equal-compartment configuration. In about 63% of the cases this envelope behaved as if it described a critically damped system, in 18% of the cases it behaved as if the system were slightly overdamped, and in the remaining 19% it corresponded to a lightly underdamped system. The average washout time constant per compartment calculated from the single-pulse response was 4.7 ± 0.8 seconds ( SD ). Repetitive stimulation was provisionally equated with a constant release of acetylcholine; its mathematical description was derived from the time integral of the single-pulse case, i.e., from a direct application of indicator-dilution theory. However, the average time constant obtained from this second type of fit was only 0.84 ± 0.4 seconds. This lower value was interpreted as a dynamic modification (perhaps nonlinear) due to accumulation of acetylcholine and probably associated with an increase in acetylcholine esterase activity.

Equations are developed to describe the energy expenditure of the human heart. As well as the external potential and kinetic energy terms, general consideration is given to other possible avenues of energy consumption. Emphasis is placed upon using mathematical variables which are readily available for experimental verification. The errors involved in assuming that mean values for the physiological parameters give reasonable estimations for the external mechanical performance are examined, and a theoretical estimation for the discrepancy in the kinetic component is presented. Logical extension of the mathematical derivation leads to a determination of cardiac external mechanical efficiency and clearly demonstrates the significance of the ventricular pressure-volume loop in this context. Finally, experimental procedures are suggested to clarify further some of the conclusions reached through the theoretical analysis.

A method has been developed to evaluate the heartrate sensitivity (S 0) of the baroreceptor system, which is defined as the decrease in heartrate per unit increase in mean arterial pressure. Average values, for the intact system, of the order of 2·23–3·65 beats min−1 mmHg−1 were found in the dog, and of 0·5 beats min−1 mmHg−1 in one pony. The carotid sinus baroreceptors add considerable, but not preponderant, sensitivity to the cardiovascular regulatory system for blood pressure. Decreases inS 0 of the order of 40% were found when these receptors were essentially eliminated by occlusion of the carotid arteries. The type of anaesthesia used has a marked influence on the sensitivity of the baroreceptor system, suggesting the possibility of using this sensitivity coefficient to evaluate the influence of anaesthetics on the homeostatic mechanisms for blood pressure.

The open-loop gainG 0 reference pressureP 0 and basal heartrateR 0 of the blood-pressure regulatory system have been estimated under four different experimental conditions by employing an aortic balloon and assuming a theoretical approach based on a 1st-order linear model. Mean values of 1·7–3·7, 75–130 mmHg, and 95–130 beats/min were obtained forG 0,P 0 andR 0, respectively. Significant variations in these parameters were observed when the anaesthetic conditions were changed. It is suggested thatG 0,P 0 andR 0 may have useful clinical applications both in characterising hypotensive and hypertensive syndromes and also in assessing the effect of anaesthetic agents.

The sinus venosus-atrial Wenckebach-Lucianiphenomenon was fully and directly demonstrated in snakes and turtles. Its pattern is similar to that shown by the phenomenon at the atrio-ventricular level, and presumably the mechanisms are the same. Since a continuum of arrhythmias was observed between the 1:1 ratio and the final 2:1 block, it is inferred that the synchronization theory of Roberge and Nadeau could be extended to this case postulating the existence of three coupled oscillators.

Durch Einführung einer Stahlnadel werden andauernde elektrische und mechanische Schwankungen erzeugt und zwar bei wechselnder Oberflächen-oxydation und Reduktion eines Quecksilbertröpfchens, das in verdünnter Säure mit K2Cr2O7 liegt. Die Schwankungen des Elektropotentials und des Widerstands wurden gemessen und zusammen mit den mechanischen Schwankungen photographiert.

Previous articleNext article No AccessRelationship of Oxygen Consumption to Heart Rate and Respiratory Parameters in Caiman scleropsSara E. Huggins, M. E. Valentinuzzi, and H. E. HoffSara E. Huggins Search for more articles by this author , M. E. Valentinuzzi Search for more articles by this author , and H. E. Hoff Search for more articles by this author PDFPDF PLUS Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinkedInRedditEmail SectionsMoreDetailsFiguresReferencesCited by Volume 44, Number 2Apr., 1971 Article DOIhttps://doi.org/10.1086/physzool.44.2.30155561 Views: 4Total views on this site Citations: 10Citations are reported from Crossref Journal History This article was published in Physiological Zoology (1928-1998), which is continued by Physiological and Biochemical Zoology (1999-present). PDF download Crossref reports the following articles citing this article:Richard Johnston, Max E. Valentinuzzi Metabolism: The Physiological Power-Generating Process: A History of Methods to Test Human Beings' \"Vital Capacity\" [Retrospectroscope], IEEE Pulse 7, no.33 (May 2016): 50–57.https://doi.org/10.1109/MPUL.2016.2538484Jonathan A. Green The heart rate method for estimating metabolic rate: Review and recommendations, Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology 158, no.33 (Mar 2011): 287–304.https://doi.org/10.1016/j.cbpa.2010.09.011Max Valentinuzzi, Andres Belalcazar Plethysmography, (Apr 2006).https://doi.org/10.1002/9780471740360.ebs0938Glenn J. Tattersall, Denis V. de Andrade, Simone P. Brito, Augusto S. Abe, William K. Milsom Regulation of ventilation in the caiman (Caiman latirostris): effects of inspired CO2 on pulmonary and upper airway chemoreceptors, Journal of Comparative Physiology B 176, no.22 (Nov 2005): 125–138.https://doi.org/10.1007/s00360-005-0034-yL.Y Lewis, R.E Gatten Aerobic metabolism of american alligators, Alligator mississippiensis, under standard conditions and during voluntary activity, Comparative Biochemistry and Physiology Part A: Physiology 80, no.33 (Jan 1985): 441–447.https://doi.org/10.1016/0300-9629(85)90065-9Herry N. Stinner Ventillation, gas exchange and blood gases in the snake, Pituophis melanoleucus, Respiration Physiology 47, no.33 (Mar 1982): 279–298.https://doi.org/10.1016/0034-5687(82)90058-5Christopher R Brown, J.P Loveridge The effect of temperature on oxygen consumption and evaporative water loss in Crocodylus niloticus, Comparative Biochemistry and Physiology Part A: Physiology 69, no.11 (Jan 1981): 51–57.https://doi.org/10.1016/0300-9629(81)90637-XH. Heatwole Voluntary submergence times of marine snakes, Marine Biology 32, no.22 (Jan 1975): 205–213.https://doi.org/10.1007/BF00388513Albert F Bennett Ventilation in two species of lizards during rest and activity, Comparative Biochemistry and Physiology Part A: Physiology 46, no.44 (Dec 1973): 653–671.https://doi.org/10.1016/0300-9629(73)90119-9M. E. Valentinuzzi, L. A. Geddes, L. E. Baker The law of impedance pneumography, Medical & Biological Engineering 9, no.33 (May 1971): 157–163.https://doi.org/10.1007/BF02474811

The classical techniques of brain stem sectioning and vagotomy are used to study possible respiratory control centers of caimans and alligators. This series of transections demonstrates the presence of (1) an inspiratory center, (2) an expiratory center, and (3) a center controlling glottal closure, all lying just below the nucleus laminaris in the medulla, but gives no evidence for an apneustic center or a pneumotaxic center in crocodilians.

Previous articleNext article No AccessOxygen Consumption of Small Caimans under Basal ConditionsS. E. Huggins, H. E. Hoff, and M. E. ValentinuzziS. E. Huggins Search for more articles by this author , H. E. Hoff Search for more articles by this author , and M. E. Valentinuzzi Search for more articles by this author PDFPDF PLUS Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinkedInRedditEmail SectionsMoreDetailsFiguresReferencesCited by Volume 44, Number 1Jan., 1971 Article DOIhttps://doi.org/10.1086/physzool.44.1.30155551 Views: 3Total views on this site Citations: 9Citations are reported from Crossref Journal History This article was published in Physiological Zoology (1928-1998), which is continued by Physiological and Biochemical Zoology (1999-present). Copyright 1972 The University of ChicagoPDF download Crossref reports the following articles citing this article:Ray Brasil Bueno de Souza, Vanessa Maria Gomes Bonfim, Vitor Passos Rios, Wilfried Klein Allometric relations of respiratory variables in Amniota: Effects of phylogeny, form, and function, Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology 252 (Feb 2021): 110845.https://doi.org/10.1016/j.cbpa.2020.110845Richard Johnston, Max E. Valentinuzzi Metabolism: The Physiological Power-Generating Process: A History of Methods to Test Human Beings' \"Vital Capacity\" [Retrospectroscope], IEEE Pulse 7, no.33 (May 2016): 50–57.https://doi.org/10.1109/MPUL.2016.2538484Max Valentinuzzi, Andres Belalcazar Plethysmography, (Apr 2006).https://doi.org/10.1002/9780471740360.ebs0938L.Y Lewis, R.E Gatten Aerobic metabolism of american alligators, Alligator mississippiensis, under standard conditions and during voluntary activity, Comparative Biochemistry and Physiology Part A: Physiology 80, no.33 (Jan 1985): 441–447.https://doi.org/10.1016/0300-9629(85)90065-9Christopher R Brown, J.P Loveridge The effect of temperature on oxygen consumption and evaporative water loss in Crocodylus niloticus, Comparative Biochemistry and Physiology Part A: Physiology 69, no.11 (Jan 1981): 51–57.https://doi.org/10.1016/0300-9629(81)90637-XG. Kauffmann Zur Abh�ngigkeit der Cochleapotentiale des Kaimans vom Stoffwechsel, von aktiven Transporten und von der Temperatur, Journal of Comparative Physiology 90, no.33 (Jan 1974): 245–273.https://doi.org/10.1007/BF00701476Albert F. Bennett, Bonnie Dalzell DINOSAUR PHYSIOLOGY: A CRITIQUE, Evolution 27, no.11 (May 2017): 170–174.https://doi.org/10.1111/j.1558-5646.1973.tb05931.xJ.R. Brett The metabolic demand for oxygen in fish, particularly salmonids, and a comparison with other vertebrates, Respiration Physiology 14, no.1-21-2 (Mar 1972): 151–170.https://doi.org/10.1016/0034-5687(72)90025-4K.H. Naifeh, S.E. Huggins, H.E. Hoff Study of the control of crocodilian respiration by anesthetic dissection, Respiration Physiology 12, no.22 (Jun 1971): 251–260.https://doi.org/10.1016/0034-5687(71)90057-0

This paper seeks to elucidate controlling mechanisms of the crocodilian respiratory pattern by observing changes in the pattern during anesthetic induction and recovery. Both chloroform and pentobarbital anesthesia produce a sequential loss of components of the respiratory pattern present in the waking animal. Typical breath groups disappear early. Breath holding ability is lost gradually, but both expiratory and inspiratory activity remain strong for some time. The loss of breath holding ability is due to gradual failure of the mechanisms controlling closure of the glottis. Expiratory activity disappears later, often involving a great prolongation of the act, leaving only periodic inspiratory activity under very deep anesthesia. There is no evidence for an apneustic center or a specific gasping center in crocodilians.

Respiratory movements of the dogfish,Squalus acanthias, were recorded by measuring the change in electrical impedance between two stainles steel needle electrodes inserted on either side of the pharyngeal cavity at the level of the gill slits. Observations indicated that the various portions of the impedance wave form could be consistently related to particular phases of the respiratory cycle of the animal. Cycle-to-cycle uniformity of the consecutive wave forms suggests that it may be possible to calibrate the impedance measurement of pharyngeal volume in these animals in truly physiological terms.

This paper examines the ventilatory phase of respiratory cycles of caimans and alligators to see if the terms diphasic and triphasic as defined by Boelaert are appropriate. Impedance pneumograms and mechanical recordings show triphasic ventilatory cycles for single breaths and for the last breath in a series, but other breaths in a series are diphasic. Experiments using EMG, an intrapulmonary pressure gauge, and a whole body plethysmograph show that (1) with respect to muscular activity, ventilation is diphasic; (2) with regard to intrapulmonary-endotracheal pressures, ventilation is triphasic; (3) with regard to total body volume, ventilation in quiet animals is diphasic, but triphasic during excitement. It is concluded that all breaths are normally diphasic and changes in intrapulmonary-endotracheal pressure, external dimensions, and impedance, simulating an E2 phase, are brought about by passive recoil of viscera. It is suggested that the term “shift” rather than the “E2 expiration” of Boelaert or the “compression” of McCutcheon is appropriate to the change seen after the last inspiration of a series or after an isolated inspiration.