Synergism between the canine left and right hemidiaphragms

2003 ◽  
Vol 94 (5) ◽  
pp. 1757-1765 ◽  
Author(s):  
André De Troyer ◽  
Matteo Cappello ◽  
Nathalie Meurant ◽  
Pierre Scillia
Keyword(s):  
Intrathoracic Pressure ◽  
Respiratory Drive ◽  
Additive Interaction ◽  
Quiet Breathing ◽  
Rib Cage ◽  
Radiographic Measurements ◽  
Airway Opening ◽  
Left And Right ◽  
The Right ◽  
Stimulation Of

Expansion of the lung during inspiration results from the coordinated contraction of the diaphragm and several groups of rib cage muscles, and we have previously shown that the changes in intrathoracic pressure generated by the latter are essentially additive. In the present studies, we have assessed the interaction between the right and left hemidiaphragms in anesthetized dogs by comparing the changes in airway opening pressure (ΔPao) obtained during simultaneous stimulation of the two phrenic nerves (measured ΔPao) to the sum of the ΔPao values produced by their separate stimulation (predicted ΔPao). The measured ΔPao was invariably greater than the predicted ΔPao, and the ratio between these two values increased gradually as the stimulation frequency was increased; the ratio was 1.10 ± 0.01 ( P < 0.05) for a frequency of 10 Hz, whereas for a frequency of 50 Hz it amounted to 1.49 ± 0.05 ( P < 0.001). This interaction remained unchanged after the rib cage was stiffened and its compliance was made linear, thus indicating that the load against which the diaphragm works is not a major determinant. However, radiographic measurements showed that stimulation of one phrenic nerve extends the inactive hemidiaphragm toward the sagittal midplane and reduces the caudal displacement of the central portion of the diaphragmatic dome. As a result, the volume swept by the contracting hemidiaphragm is smaller than the volume it displaces when the contralateral hemidiaphragm also contracts. These observations indicate that 1) the left and right hemidiaphragms have a synergistic, rather than additive, interaction on the lung; 2) this synergism operates already during quiet breathing and increases in magnitude when respiratory drive is greater; and 3) this synergism is primarily related to the configuration of the muscle.

scholarly journals Interaction between left and right intercostal muscles in airway pressure generation

2000 ◽  
Vol 88 (3) ◽  
pp. 817-820 ◽  
Author(s):  
Matteo Cappello ◽  
André de Troyer
Keyword(s):  
Opening Pressure ◽  
Rib Cage ◽  
Linear Elastic ◽  
Inspiratory Muscles ◽  
Wide Range ◽  
Airway Opening ◽  
Left And Right ◽  
The Difference ◽  
The Right ◽  
Pressure Changes

The interactions between the different rib cage inspiratory muscles in the generation of pleural pressure remain largely unknown. In the present study, we have assessed in dogs the interactions between the parasternal intercostals and the interosseous intercostals situated on the right and left sides of the sternum. For each set of muscles, the changes in airway opening pressure (ΔPao) obtained during separate right and left activation were added, and the calculated values (predicted ΔPao) were then compared with the ΔPao values obtained during symmetric, bilateral activation (measured ΔPao). When the parasternal intercostals in one or two interspaces were activated, the measured ΔPao was commonly greater than the predicted value. The difference, however, was only 10%. When the interosseous intercostals were activated, the measured ΔPao was nearly equal to the predicted value. These observations strengthen our previous conclusion that the pressure changes produced by the rib cage inspiratory muscles are essentially additive. As a corollary, the rib cage can be considered as a linear elastic structure over a wide range of distortion.

Effect of lung volume on the respiratory action of the canine pectoral muscles

1992 ◽  
Vol 73 (6) ◽  
pp. 2408-2412 ◽  
Author(s):  
S. R. Muza ◽  
G. J. Criner ◽  
S. G. Kelsen
Keyword(s):  
Electrical Stimulation ◽  
Lung Volume ◽  
Intrathoracic Pressure ◽  
Pectoral Muscle ◽  
Positive Pressure ◽  
Rib Cage ◽  
Mechanical Coupling ◽  
Negative Intrathoracic Pressure ◽  
Pressure Changes ◽  
Stimulation Of

Lung volume influences the mechanical action of the primary inspiratory and expiratory muscles by affecting their precontraction length, alignment with the rib cage, and mechanical coupling to agonistic and antagonistic muscles. We have previously shown that the canine pectoral muscles exert an expiratory action on the rib cage when the forelimbs are at the torso's side and an inspiratory action when the forelimbs are held elevated. To determine the effect of lung volume on intrathoracic pressure changes produced by the canine pectoral muscles, we performed isolated bilateral supramaximal electrical stimulation of the deep pectoral and superficial pectoralis (descending and transverse heads) muscles in 15 adult supine anesthetized dogs during hyperventilation-induced apnea. Lung volume was altered by application of a negative or positive pressure (+/- 30 cmH2O) to the airway. In all animals, selective electrical stimulation of the descending, transverse, and deep pectoral muscles with the forelimbs held elevated produced negative intrathoracic pressure changes (i.e., an inspiratory action). Moreover, with the forelimbs elevated, increasing lung volume decreased both pectoral muscle fiber precontraction length and the negative intrathoracic pressure changes generated by contraction of each of these muscles. Conversely, with the forelimbs along the torso, increasing lung volume lengthened pectoral muscle precontraction length and augmented the positive intrathoracic pressure changes produced by muscle contraction (i.e., an expiratory action). These results indicate that lung volume significantly affects the length of the canine pectoral muscles and their mechanical actions on the rib cage.

scholarly journals Asymmetry of reinforcing properties of the lateral hypothalamus in the self-stimulation test

2018 ◽  
Vol 16 (2) ◽  
pp. 37-41
Author(s):  
Nikolay S Efimov ◽  
Yulia N Bessolova ◽  
Inessa V Karpova ◽  
Andrei A Lebedev ◽  
Petr D Shabanov
Keyword(s):  
Electrical Stimulation ◽  
Lateral Hypothalamus ◽  
The Self ◽  
Stimulation Test ◽  
Reinforcing Agent ◽  
Male Wistar Rats ◽  
Left And Right ◽  
The Right ◽  
Self Stimulation ◽  
Stimulation Of

In the protocols of modern pharmacological studies of a self-stimulation reaction in rodents, stimulating electrodes are implanted as a rule unilaterally. The reinforcing properties of the left and right hypothalamus were suggested to be identical. The aim of the study was to clear up if the possibilities of the left and right hypothalamus to produce self-stimulation are similar or not. Methods. The study was carried out on adult male Wistar rats. The electrodes were implanted into the lateral hypothalamus bilaterally. The rats, in which an approach reaction was observed, learned self-stimulation in the Skinner box with stimulation of the left or right hypothalamus as a reinforcing agent descending thresholds of stimulation up to minimal one. Results. Self-stimulation of the left hypothalamus gave an approach reaction in the majority of rats (81.8%), self-stimulation reaction was developed in 72.7% of rats. Only 46.2% rats reacted on stimulation of the right hypothalamus, self-stimulation reaction was developed in 30.8% of rats. The thresholds of positive and negative reactions registered after electrical stimulation of both sides of hypothalamus were significantly differed (H(3, N = 31) = 14,92; p = 0,002). And these changes were not connected with lateralization but with sign of reaction: in general the thresholds of approach reaction were higher than thresholds of avoidance. Conclusion. In the paper, the fact of different possibility of approach reaction and self-stimulation development as a result of electrical stimulation of the left and right hypothalamus in rats has been described. After stimulation of the left hypothalamus, a possibility to receive positive reaction and to form self-stimulation on its basis is higher than after stimulation of the right hypothalamus. (For citation: Efimov NS, Bessolova YN, Karpova IV, et al. Asymmetry of reinforcing properties of the lateral hypothalamus in the self-stimulation test. Reviews on Clinical Pharmacology and Drug Therapy. 2018;16(2):37-41. doi: 10.17816/RCF16237-41).

Antagonistic interaction of laryngeal and central chemoreceptor respiratory reflexes

1992 ◽  
Vol 72 (2) ◽  
pp. 643-649 ◽  
Author(s):  
B. N. Van Vliet ◽  
M. Uenishi
Keyword(s):  
Superior Laryngeal Nerve ◽  
Control Mechanisms ◽  
Respiratory Drive ◽  
Absolute Level ◽  
Afferent Stimulation ◽  
Airway Reflex ◽  
Central Inspiratory Activity ◽  
Inspiratory Activity ◽  
The Right ◽  
Stimulation Of

Stimulation of laryngeal afferent fibers evokes a profound reflex inhibition of central respiratory drive. The interaction of this airway reflex with chemoreceptive ventilatory control mechanisms is poorly understood. The present study was undertaken to determine whether there is significant interaction between the effects of central chemoreceptor and laryngeal afferent stimulation on central inspiratory activity and, if so, to also determine the nature of the interaction. The effect of electrical stimulation of the superior laryngeal nerve (SLN) on the timing and intensity of central inspiratory activity was determined from the rectified and filtered phrenic neurogram in 10 dogs. Each dogs was decerebrated, artificially ventilated, vagotomized, and had the carotid bodies denervated. In each case, stimulation of the right SLN at 3 and 10 Hz caused a frequency-dependent slowing or arrest of central inspiratory activity. Increases in arterial PCO2 (PaCO2) attenuated the absolute level of inhibition of central inspiratory activity recorded during both SLN stimulation and control periods. Tp clarify the nature of the interaction between chemoreceptor and laryngeal afferent stimulation, the relationship between PaCO2 and central inspiratory activity was investigated during stimulation of the SLN at 0, 3, and 10 Hz. Control central inspiratory activity increased as a sigmoidal function of PaCO2. This sigmoidal relationship was greatly depressed during SLN stimulation but did not appear to be shifted along the PaCO2 axis. The results of this study therefore suggest that the interaction between central chemoreceptor and laryngeal afferent stimulation is multiplicative: the inhibition of the central inspiratory activity is mediated by an attenuation and not a resetting of central chemoreflexes.

scholarly journals VAGAL REGULATION OF INTRACARDIAC SHUNTING IN THE TURTLE PSEUDEMYS SCRIPTA

1994 ◽  
Vol 186 (1) ◽  
pp. 109-126 ◽  
Author(s):  
J. Hicks ◽  
S. Comeau
Keyword(s):  
Blood Flow ◽  
Electrical Stimulation ◽  
Pulmonary Artery ◽  
Left Atrium ◽  
Jugular Vein ◽  
Left And Right ◽  
The Right ◽  
Right Atria ◽  
Intracardiac Shunting ◽  
Stimulation Of

Two principal hypotheses account for intracardiac shunting in reptiles. The ‘pressure shunting’ hypothesis proposes that there is no fuctional separation between the ventricular cava during systole. The ‘washout shunting’ hypothesis suggests that the cavum pulmonale is functionally separated from the rest of the ventricle during systole. The purpose of this study was to test the two principal hypotheses in a turtle, Pseudemys scripta, after inducing a right-to-left shunt by electrical stimulation of the vagus nerve. Animals were anaesthetized with sodium pentobarbital (30–40 mg kg-1), tracheotomized and mechanically ventilated. Two experimental groups were used. Both groups had the right and left cervical vagi exposed and sectioned and silver bipolar electrodes were attached for electrical stimulation. In addition, cardiac function was evaluated by determining the pulmonary blood flow, pulmonary arterial pressure, peak systolic pressure in the cavum pulmonale, central arterial pressure, pulmonary vascular resistance and heart rate. In group I, hydrogen electrodes were inserted into the right aorta, the left aorta and the pulmonary artery. Hydrogen, dissolved in saline, was infused into the left atrium, jugular vein and cavum pulmonale. Blood flow from these sites was deduced from detection of a H2 signal in the right and left aortae and the pulmonary artery. In group II, catheters were inserted in the left and right atria and aortae for the measurement of blood gases. For both groups, the protocol consisted of control periods and periods of electrical stimulation of the efferent and afferent ends of the vagus nerve. During the control periods, infusion of a H2 solution into either the left atrium or the jugular vein resulted in the detection of H2 in the right and left aortae and the pulmonary artery. This suggested that both right-to-left and left-to-right intracardiac shunts were present. H2 infused into the cavum pulmonale was always detected in the pulmonary artery but never in the left or right aortae. During stimulation of the right vagal efferents, a bradycardia developed (heart rate declined by 65 %), pulmonary blood flow was reduced by 73 % and pulmonary vascular resistance increased by 158 %. This was accompanied by a reduction in the PO2 of both the right and left aortae, although the PO2 of the left and right atria remained constant. Under these conditions, H2 infused into the jugular vein and the left atrium was detected in the right and left aortae and the pulmonary artery of all animals studied. Infusion of H2 into the cavum pulmonale was detected in the right and left aortae in only two animals. The results supported the washout mechanism for right-to-left intracardiac shunting.

scholarly journals Occipital Petalia and Albinism: A Study of Interhemispheric VEP Asymmetries in Albinism with No Nystagmus

2019 ◽  
Vol 8 (6) ◽  
pp. 802 ◽  
Author(s):  
Alkiviades Liasis ◽  
Sian E. Handley ◽  
Ken K. Nischal
Keyword(s):  
Right Hemisphere ◽  
Normal Subjects ◽  
Visual Pathway ◽  
Field Pattern ◽  
Pattern Reversal ◽  
Full Field ◽  
Pathway Function ◽  
Left And Right ◽  
The Right ◽  
Stimulation Of

The purpose of this study was to assess chiasmal misrouting in a cohort of children with albinism with no nystagmus using hemifield visual evoked potentials (VEP) measures. Methods: Monocular VEPs were recorded and analyzed from three electrodes (O1, Oz, and O2 referred to Fz) from 16 children with albinism without nystagmus. Pattern reversal (full field and hemifield stimulation), full field pattern appearance and flash stimuli were used to evoke VEPs for each eye. Results: The amplitude of the pattern reversal VEPs to stimulation of the hemifield corresponding to the crossing pathways were as expected significantly larger than those to the non-crossing in each eye ((right eye p = 0.000004), (left eye p = 0.001)). Pattern reversal VEPs recorded from the left hemisphere were also larger than those from the right and most evident when comparing the crossing pathways of each eye (p = 0.004). Conclusions: This study has demonstrated electrophysiological differences in visual pathway function of the left and right hemisphere in subjects with albinism like that previously described in controls. Nasal field stimulation activated crossing and non-crossing pathways in patients with albinism and as a result, nasal hemifield VEPs in albinism are less lateralized compared to what is found in normal subjects.

Effect of inflation on the interaction between the left and right hemidiaphragms

2005 ◽  
Vol 99 (4) ◽  
pp. 1301-1307 ◽  
Author(s):  
André De Troyer ◽  
Matteo Cappello ◽  
Pierre Scillia
Keyword(s):  
Lung Volume ◽  
Muscle Tension ◽  
Abdominal Pressure ◽  
Lung Volumes ◽  
Radiographic Measurements ◽  
Airway Opening ◽  
Residual Capacity ◽  
Left And Right ◽  
Predicted Values ◽  
Pressure Changes

At resting end expiration [functional residual capacity (FRC)], the actions of the left and right hemidiaphragms on the lung are synergistic. However, the synergism decreases in magnitude as muscle tension decreases. Therefore, the hypothesis was tested in anesthetized dogs that the degree of synergism between the two hemidiaphragms also decreases with increasing lung volume. In a first experiment, the changes in airway opening pressure (ΔPao) and abdominal pressure (ΔPab) obtained during simultaneous stimulation of the left and right phrenic nerves (measured changes in pressure) at different lung volumes were compared with the sum of the pressure changes produced by their separate stimulation (predicted changes in pressure). Although the pressure changes decreased markedly with increasing lung volume, the measured ΔPao and ΔPab were substantially greater than the predicted values at all lung volumes. The ratio of the measured to the predicted ΔPao, in fact, remained constant. In a second experiment, radiographic measurements showed that the fractional shortening of the muscle during bilateral contraction at high lung volumes was similar to that during unilateral contraction. During unilateral contraction at high lung volumes, however, the passive hemidiaphragm moved in the cranial direction, whereas, during unilateral contraction at FRC, it moved in the caudal direction. These observations indicate that 1) for a given muscle tension, the synergism between the two halves of the diaphragm is greater at high lung volumes than at FRC; and 2) this difference is primarily related to the greater distortion of the muscle configuration.

On the respiratory function of the ribs

2002 ◽  
Vol 92 (4) ◽  
pp. 1642-1646 ◽  
Author(s):  
Matteo Cappello ◽  
André De Troyer
Keyword(s):  
Respiratory Function ◽  
Volume Expansion ◽  
Critical Role ◽  
Intercostal Muscle ◽  
Opening Pressure ◽  
Rib Cage ◽  
Muscle Shortening ◽  
Airway Opening ◽  
Anesthetized Dogs ◽  
Stimulation Of

To assess the respiratory function of the ribs, we measured the changes in airway opening pressure (Pao) induced by stimulation of the parasternal and external intercostal muscles in anesthetized dogs, first before and then after the bony ribs were removed from both sides of the chest. Stimulating either set of muscles with the rib cage intact elicited a fall in Pao in all animals. After removal of the ribs, however, the fall in Pao produced by the parasternal intercostals was reduced by 60% and the fall produced by the external intercostals was eliminated. The normal outward curvature of the rib cage was also abolished in this condition, and when the curvature was restored by a small inflation, external intercostal stimulation consistently elicited a rise rather than a fall in Pao. These findings thus confirm that the ribs play a critical role in the act of breathing by converting intercostal muscle shortening into lung volume expansion. In addition, they carry the compression that is required to balance the pressure difference across the chest wall.

Phosphene perceptions and safety of chronic visual cortex stimulation in a blind subject

2020 ◽  
Vol 132 (6) ◽  
pp. 2000-2007 ◽  
Author(s):  
Soroush Niketeghad ◽  
Abirami Muralidharan ◽  
Uday Patel ◽  
Jessy D. Dorn ◽  
Laura Bonelli ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Adverse Events ◽  
Clinical Intervention ◽  
Occipital Cortex ◽  
Neuronal Population ◽  
Serious Adverse Events ◽  
Stimulation Parameters ◽  
The Right ◽  
Visual Cortical ◽  
Stimulation Of

Stimulation of primary visual cortices has the potential to restore some degree of vision to blind individuals. Developing safe and reliable visual cortical prostheses requires assessment of the long-term stability, feasibility, and safety of generating stimulation-evoked perceptions.A NeuroPace responsive neurostimulation system was implanted in a blind individual with an 8-year history of bare light perception, and stimulation-evoked phosphenes were evaluated over 19 months (41 test sessions). Electrical stimulation was delivered via two four-contact subdural electrode strips implanted over the right medial occipital cortex. Current and charge thresholds for eliciting visual perception (phosphenes) were measured, as were the shape, size, location, and intensity of the phosphenes. Adverse events were also assessed.Stimulation of all contacts resulted in phosphene perception. Phosphenes appeared completely or partially in the left hemifield. Stimulation of the electrodes below the calcarine sulcus elicited phosphenes in the superior hemifield and vice versa. Changing the stimulation parameters of frequency, pulse width, and burst duration affected current thresholds for eliciting phosphenes, and increasing the amplitude or frequency of stimulation resulted in brighter perceptions. While stimulation thresholds decreased between an average of 5% and 12% after 19 months, spatial mapping of phosphenes remained consistent over time. Although no serious adverse events were observed, the subject experienced mild headaches and dizziness in three instances, symptoms that did not persist for more than a few hours and for which no clinical intervention was required.Using an off-the-shelf neurostimulator, the authors were able to reliably generate phosphenes in different areas of the visual field over 19 months with no serious adverse events, providing preliminary proof of feasibility and safety to proceed with visual epicortical prosthetic clinical trials. Moreover, they systematically explored the relationship between stimulation parameters and phosphene thresholds and discovered the direct relation of perception thresholds based on primary visual cortex (V1) neuronal population excitation thresholds.

Comparison of the efficiency of the indexes of Pont and Korkhause with Kernott technique in patients with narrowing of maxilla

2020 ◽  
Vol 20 (3) ◽  
pp. 199-203
Author(s):  
O. I. Admakin ◽  
I. A. Solop ◽  
A. D. Oksentyuk
Keyword(s):  
Dental Treatment ◽  
Standard Analysis ◽  
Clinical Hospital ◽  
Control Models ◽  
Diagnostic Models ◽  
Left And Right ◽  
The Asymmetry ◽  
The Right ◽  
The University ◽  
Medical University

Relevance. The narrowing of the maxilla is one of the most common pathologies in orthodontics. Recent studies show that the narrowing is always asymmetric which is connected to the rotation of the maxilla. To choose the treatment correctly one need a calculation that reveals the asymmetry, which is impossible with using standard indexes.Purpose – to compare efficiency of indexes of Pont and Korkhause with the Kernott's method in patients with narrowing of the maxilla.Materials and methods. The study involved 35 children aged from 8 to 12 years old undergoing dental treatment in the University Children's Clinical Hospital of the First Moscow State Medical University with no comorbidities. For every patient a gypsum model was prepared and after that to carry out the biometrical calculation. In this study two indexes were used: Pont's index and Korkhause's; using this standard analysis the narrowing of the maxilla was revealed. After using Pont's Index and Korkhaus analysis all the models were calculated by the method of Kernott with Kernott's dynamic pentagon.Results. As a result of the analysis of the control diagnostic models a narrowing of the maxilla in 69% of cases (n = 24) was revealed in all cases, the deviation of the size of the dentition was asymmetric. Thus, 65% of the surveyed models showed a narrowing on the right. This narrowing was of a different severity and averaged 15 control models.Conclusions. This shows that for the biometrics of diagnostic models it is necessary to use methods that allow to estimate the width of the dentition rows on the left and on the right separately. To correct the asymmetric narrowing of the dentition, it is preferable to use non-classical expanding devices that act equally on the left and right sides separetly.

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