Activity of canine in situ left atrial ganglion neurons

1990 ◽  
Vol 259 (4) ◽  
pp. H1207-H1215 ◽  
Author(s):  
J. A. Armour ◽  
D. A. Hopkins
Keyword(s):  
Left Atrial ◽  
Systolic Pressure ◽  
Ventral Surface ◽  
Identified Neurons ◽  
Related Activity ◽  
Ganglionated Plexi ◽  
Respiratory Dynamics ◽  
Ganglion Neurons ◽  
Fat Pads

The responses of 135 spontaneously active neurons were recorded from ganglionated plexi located in the three epicardial fat pads on the ventral surface of the left atrium of ten dogs. Ganglia, some of which were adjacent to the recording sites, containing varying numbers of neurons were identified throughout these fat pads. Spontaneous activity in 50% of the identified neurons was correlated with specific phases of the cardiac cycle when arterial systolic pressure was between approximately 70 and 180 mmHg and in 28% it was correlated with the respiratory cycle. More neurons displaying cardiovascular-related activity were recorded when systolic pressure was increased after administration of positive inotropic agents or aortic occlusion. However, when systolic pressure increased above approximately 150 mmHg the number of active neurons decreased, and when pressure reached approximately 180 mmHg no activity was recorded. The activity of 36% of identified neurons was altered when discrete regions of the heart, great thoracic vessels, lungs, neck, upper limb, chest wall, or abdominal wall were mechanically distorted by gentle touch. After acute decentralization of the intrathoracic nervous system some neurons still displayed spontaneous cardiovascular- or respiratory-related activity. Single stimuli or trains of stimuli delivered to the vagosympathetic complexes, stellate ganglia, or cardiopulmonary nerves activated neurons in intact or acutely decentralized preparations. It is concluded that ventral left atrial ganglionated plexi neurons display activity related to cardiovascular or respiratory dynamics, and that these neurons are influenced by sympathetic and parasympathetic efferent axons, as well as by cardiac and other mechanoreceptors.

Neuronal activity recorded extracellularly from in situ canine mediastinal ganglia

1988 ◽  
Vol 66 (1) ◽  
pp. 119-127 ◽  
Author(s):  
J. A. Armour ◽  
R. D. Janes
Keyword(s):  
Vena Cava ◽  
Systolic Pressure ◽  
Thoracic Wall ◽  
Identified Neurons ◽  
Positive Pressure ◽  
Related Activity ◽  
Local Circuit ◽  
Local Circuit Neurons ◽  
Ganglion Neurons

Spontaneous activity of 226 neurons was recorded from in situ mediastinal ganglia in 10 dogs. Forty-two percent of these were active during specific phases of the cardiac cycle, primarily during systole. Cardiovascular-related activity occurred when systolic pressure was between ~70 and 185 mmHg (1 mmHg = 133.3 Pa) whether the pressure was altered by positive inotropic pharmacological agents or cross clamping of the aorta. Twenty percent of the identified neurons displayed respiratory-related activity which occurred during positive pressure inflation or deflation. Thirty-eight percent of the identified neurons displayed bursts of activity or sporadic activity. The activity of 17% of the identified neurons was altered by gentle mechanical distortion of localized regions of the neck, left elbow, ventral thoracic wall, ventral abdominal wall, superior vena cava, right ventricle, or aorta. In the majority of instances cardiovascular- or respiratory-related activity persisted following acute decentralization, indicating that neurons in mediastinal ganglia can function in the absence of influences of central nervous system neurons. Five percent of the identified neurons were activated by single 1–4 ms, 10–20 V stimuli delivered at 0.5 Hz to the nerves connected with either the cranial or the caudal poles of the mediastinal ganglion or the ansae. These neurons were activated after a fixed latency when 0.5 Hz was used and in most instances when 10 Hz was used. These data indicate that 5% or less of the neurons identified projected axons out of the mediastinal ganglia investigated. As the remainder of the neurons identified were not consistently activated after single stimuli delivered individually to the nerves connected directly or indirectly with the mediastinal ganglion, they presumably did not project axons out of the ganglion and thus were considered to be local circuit neurons. Since a number of these local circuit neurons were activated by trains of stimuli delivered to the ipsilateral cardiopulmonary nerves, ansae, rami, sympathetic chain, or cervical vagosympathetic complex, it appears that neural information from a number of sources can modify the behaviour of mediastinal ganglion neurons, substantiating the evidence obtained when various tissues were distorted. Some of the neurons in mediastinal ganglia continued to be activated by trains of stimuli following the administration of hexamethonium, atropine, propranolol, and phentolamine, albeit usually with different latencies of activation. These data support the contention that synaptic mechanisms other than cholinergic and adrenergic ones may exist in mediastinal ganglia, as has been proposed to occur with respect to neurons in the major intrathoracic ganglia. The results of the present experiments indicate that neurons in mediastinal ganglia are involved in cardiovascular and respiratory regulation and that they can be influenced by neural structures in a variety of tissues, some of which are relatively remote from the ganglion. It appears that some of these may be local circuit neurons. Thus neurons in ganglia adjacent to the heart and lungs can behave similarly to neurons located in the middle cervical and stellate ganglia.

Activity of in vivo canine cardiac plexus neurons

1988 ◽  
Vol 255 (4) ◽  
pp. H789-H800 ◽  
Author(s):  
M. Gagliardi ◽  
W. C. Randall ◽  
D. Bieger ◽  
R. D. Wurster ◽  
D. A. Hopkins ◽  
...  
Keyword(s):  
Cardiac Cycle ◽  
Pulmonary Veins ◽  
Systolic Pressure ◽  
Identified Neurons ◽  
Fat Pad ◽  
Respiratory Dynamics ◽  
The Right ◽  
Ganglion Neurons ◽  
Ganglionated Plexus

The activity of 394 spontaneously active neurons located in the ganglionated plexus of the ventral epicardial fat pad overlying the right atrium and pulmonary veins was recorded. Ganglia that contained various numbers of neurons, many with two or more nucleoli, were identified adjacent to the recording sites. Spontaneous activity was correlated with the cardiac cycle in 39% and with the respiratory cycle in 8% of the identified neurons. Neuronal activity occurred in specific phases of the cardiac cycle when arterial pressure was between approximately 70 and 175 mmHg. During increases in systolic pressure induced by positive inotropic agents or aortic occlusion, responses of neurons that displayed cardiovascular-related activity were enhanced. These responses persisted after acute decentralization. The activity of 14% of all identified neurons was altered when discrete regions of the heart, great thoracic vessels, or lungs were mechanically distorted by gentle touch. Trains of stimuli, but not single stimuli, delivered to the vagosympathetic complexes, stellate ganglia, or cardiopulmonary nerves activated ganglionic neurons in intact or acutely decentralized preparations. It is concluded that the activity of some cardiac ganglion neurons is related to cardiovascular or respiratory dynamics and that some of these neurons receive inputs from sympathetic and parasympathetic efferent axons as well as from cardiac mechanoreceptors.

Activity of in vivo canine ventricular neurons

1990 ◽  
Vol 258 (2) ◽  
pp. H326-H336 ◽  
Author(s):  
J. A. Armour ◽  
D. A. Hopkins
Keyword(s):  
Spontaneous Activity ◽  
Cardiac Cycle ◽  
Identified Neurons ◽  
Related Activity ◽  
Pulmonary Tissue ◽  
Anesthetized Dogs ◽  
The Central Nervous System ◽  
Respiratory Dynamics ◽  
Ganglionated Plexus

The spontaneous activity of 113 neurons located in the ganglionated plexus in the epicardial fat overlying the cranial portion of the ventral intraventricular groove and the origin of the circumflex coronary artery was recorded in ten anesthetized dogs. Ganglia that contained varying numbers of neurons, some with two or more nucleoli, were subsequently identified anatomically in the vicinity of the recording sites. Spontaneous activity was correlated with the cardiac cycle in 81% and with the respiratory cycle in 17% of the identified neurons. The spontaneous cardiovascular-related activity occurred in relation to specific phases of the cardiac cycle when arterial pressure was between approximately 80 and 175 mmHg. When systolic pressures fell below approximately 80 mmHg or increased above approximately 175 mmHg, neurons displaying cardiovascular-related activity were inactive. The activity of 62% of all identified neurons was altered when discrete regions of the heart or pulmonary tissue were mechanically distorted by gentle touch. In many instances mechanical distortions of tissues were still able to alter neuronal activity following acute decentralization. Single stimuli or trains of stimuli delivered to the vagosympathetic complexes, stellate ganglia, or cardiopulmonary nerves generated bursts of activity in ganglionic neurons. Spontaneous activity occurred whether the ganglia were connected to the central nervous system or acutely decentralized. It is concluded that some neurons located on the canine ventricle display spontaneous activity that is related to cardiovascular or respiratory dynamics. The results also demonstrate that ventricular neurons can be influenced by sympathetic or parasympathetic efferent axons as well as cardiac mechanoreceptors.

Neuronal activity recorded extracellularly in chronically decentralized in situ canine middle cervical ganglia

1986 ◽  
Vol 64 (7) ◽  
pp. 1038-1046 ◽  
Author(s):  
J. A. Armour
Keyword(s):  
Nervous System ◽  
Thoracic Wall ◽  
Identified Neurons ◽  
Pulmonary Tissue ◽  
Local Circuit ◽  
Local Circuit Neurons ◽  
Cervical Ganglion ◽  
Cervical Ganglia ◽  
Ganglion Neurons

In chronically decentralized in situ middle cervical ganglia of 10 dogs, 279 spontaneously active neurons were identified. One hundred and ten (39%) of these were spontaneously active during specific phases of the cardiac cycle, primarily during systole, and the activity of nearly half of these cardiovascular-related neurons was modified by gentle mechanical distortion of the vena cavae, heart, or thoracic aorta. Another 60 (22%) of the identified neurons had respiratory – related activity, but the activity of only 2 of them was modified by gentle mechanical distortion of pulmonary tissue. Twenty-nine of the other 109 identified neurons were activated by gentle mechanical distortion of localized regions of the neck, ventral thoracic wall, or ventral abdominal wall. Because of the presence of activity in the chronically decentralized middle cervical ganglion, these data infer that some afferent neurons are located in the thoracic autonomic nervous system. Some middle cervical ganglion neurons were activated by single 1–4 ms stimuli delivered to a nerve connected to the ganglion. During repetitive stimuli delivered at 0.5 Hz none were activated after a fixed latency following the stimuli. Many more neurons were activated by 10- to 200-ms trains of 1–4 ms stimuli delivered with interstimulus intervals of 1–10 ms. The majority of these neurons could still be activated electrically after the administration of cholinergic and adrenergic pharmacological blocking agents. As the spontaneously active neurons, as well as those which were not spontaneously active, which were recorded were not consistently activated by single 1–4 ms stimuli delivered individually to every nerve connected to the middle cervical ganglion, they presumably did not project axons into these nerves and thus are presumed not to be afferent or efferent postganglionic neurons but rather to be local circuit neurons. It is concluded that local circuit neurons in the middle cervical ganglion are involved in regulating cardiovascular, respiratory, and other tissues and can function independent of neurons in the central nervous system.

scholarly journals Left Atrial Strain Identifies Increased Atrial Ectopy in Patients with Beta-Thalassemia Major

Diagnostics ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 1
Author(s):  
Maria Vlachou ◽  
Vasileios Kamperidis ◽  
Efthymia Vlachaki ◽  
Georgios Tziatzios ◽  
Despoina Pantelidou ◽  
...  
Keyword(s):  
Blood Transfusion ◽  
Left Atrial ◽  
Systolic Pressure ◽  
Thalassemia Major ◽  
Beta Thalassemia ◽  
Tape Recording ◽  
Blood Transfusions ◽  
Systolic Strain ◽  
Peak Systolic Strain ◽  
Beta Thalassemia Major

Patients with beta-thalassemia major (β-ΤΜ) may develop cardiac arrhythmias through a multifactorial mechanism. The current study evaluated the association of cardiac structure and function on echocardiography with atrial ectopic burden on 24-hour tape recording in β-ΤΜ patients. This prospective study included consecutive β-ΤΜ patients. Demographic, laboratory, echocardiographic, cardiac magnetic resonance (CMR) T2* and 24-hour tape recording data were prospectively collected. The patients were classified according to the median value of premature atrial contractions (PACs) on 24-hour tape. In total, 50 β-TM patients (37.6 ± 9.1 years old, 50% male) were divided in 2 groups; PACs ≤ 24/day and > 24/day. Patients with PACs > 24/day were treated with blood transfusion for a longer period of time (39.0 ± 8.6 vs. 32.0 ± 8.9 years, p < 0.007), compared to their counterparts. Older age (OR: 1.121, 95% CI: 1.032–1.217, p = 0.007), longer duration of blood transfusion (OR:1.101, 95% CI:1.019–1.188, p = 0.014), larger LV end-diastolic diameter (OR: 4.522, 95% CI:1.009–20.280, p = 0.049), higher values of LA peak systolic strain (OR: 0.869, 95% CI: 0.783–0.964, p = 0.008), higher MV E/E′ average (OR: 1.407, 95% CI: 1.028–1.926, p = 0.033) and higher right ventricular systolic pressure (OR: 1.147, 95% CI: 1.039–1.266, p = 0.006) were univariably associated with PACs > 24/day. LA peak systolic strain remained significantly associated with PACs > 24/day after adjusting for the duration of blood transfusions or for CMR T2*. The multivariable model including blood transfusion duration and LA peak systolic strain was the most closely associated with PACs > 24/day. Receiver operating characteristic curve analysis identified a left atrial peak systolic strain of 31.5%, as the best cut-off value (83% sensitivity, 68% specificity) for prediction of PACs > 24/day. In β-TM patients, LA peak systolic strain was associated with the atrial arrhythmia burden independently to the duration of blood transfusions and CMR T2*.

Flow of edema fluid into pulmonary airways

1983 ◽  
Vol 55 (4) ◽  
pp. 1262-1268 ◽  
Author(s):  
G. R. Mason ◽  
R. M. Effros
Keyword(s):  
Evans Blue ◽  
Left Atrial ◽  
Blue Dye ◽  
Edema Formation ◽  
Evans Blue Dye ◽  
Colloid Particles ◽  
Edema Fluid ◽  
Pulmonary Airways ◽  
99Mtc Sulfur Colloid

An in situ rabbit preparation was used to characterize the manner in which edema fluid enters the airways when left atrial pressures are elevated. The airways were initially filled with fluid to minimize retrograde flow of edema fluid into the alveoli. The airway solution contained 125I-albumin and in some studies [14C]sucrose, and the lungs were perfused with a comparable solution which contained albumin labeled with Evans blue dye and 99mTc-diethylenetriaminepentaacetate (DTPA) or 99mTc-sulfur-colloid particles (0.4-1.7 micron diam). After 30 min of perfusion, fluid was pumped from the airways into serial tubes. When left atrial pressures were low, there was very little transfer of labels detectable between the airway and perfusate solutions. However when left atrial pressures were increased to either 15 or 22 cmH2O, fluid entered the airways containing approximately the same concentrations of Evans blue dye and 99mTc-DTPA as those present in the perfusate. In contrast, the concentration of colloid particles averaged less than 5% perfusate concentrations, indicating that the fluid had not escaped through a tear in the barriers separating the vascular and airway compartments. Concentrations of the perfusate fluid and indicators were highest in the initial samples pumped from the airways. These observations suggest that some of the fluid entering the airways may be derived from peribronchial cuffs or that there are marked regional differences in edema formation from alveoli.

Rhythm effects on contractility of the beating isovolumic left ventricle

1960 ◽  
Vol 199 (6) ◽  
pp. 1115-1120 ◽  
Author(s):  
B. Lendrum ◽  
H. Feinberg ◽  
E. Boyd ◽  
L. N. Katz
Keyword(s):  
Heart Rate ◽  
Left Ventricle ◽  
Systolic Pressure ◽  
Ventricular Volume ◽  
Contractile Force ◽  
Postextrasystolic Potentiation ◽  
Pressure Development ◽  
Induced Changes ◽  
Electrical Alternans

Variation in contractile force of the isovolumic contracting left ventricle of the dog was studied in open-chested in situ hearts. The electrocardiogram and intraventricular pressures were recorded at various heart volumes. Spontaneous changes in heart rate and rhythm occurred at all volumes. Isovolumic systolic pressure development (contractile force) varied with rate and rhythm. Contractile force increased with heart rate (treppe) regardless of pacemaker origin. When a premature beat was followed by a compensatory pause, the premature beat showed a decrease and the next beat an increase in contractile force (postextrasystolic potentiation). The magnitude of the changes varied directly with the prematurity of the beat. Mechanical alternans was observed with electrical alternans, despite the absence of significant volume change. Rate-induced changes, postextrasystolic potentiation and mechanical alternans were additive when they occurred simultaneously. For practical purposes, ventricular volume (filling), hence muscle fiber length, remained constant during these rate and rhythm change, therefore could not affect the strength of contraction. Contractile force changes directly attributable to rate and rhythm changes do, therefore, occur in the intact mammalian heart.

Inotropic effects of ejection are myocardial properties

1994 ◽  
Vol 266 (3) ◽  
pp. H1202-H1213 ◽  
Author(s):  
P. P. De Tombe ◽  
W. C. Little
Keyword(s):  
Systolic Pressure ◽  
Left Ventricular ◽  
Negative Effects ◽  
Inotropic Effects ◽  
Contraction Duration ◽  
Loading System ◽  
Positive Effect ◽  
Isolated Rat

Recent studies in isolated and in vivo canine hearts have suggested that the left ventricular end-systolic pressure (LVPes) of ejecting beats is the net result of a balance between positive and negative effects of ejection. At present, it is unknown whether these ejection effects are merely a ventricular chamber property or represent a fundamental myocardial property. Accordingly, we examined the effects of ejection in eight isolated rat cardiac trabeculae at the sarcomere level. We approximated in situ sarcomere shortening patterns using an iterative computer loading system. Six isovolumic contractions were compared with four ejecting contractions. The superfusing solution contained either 0.7 mM Ca2+ or 0.65 mM Sr2+ plus 0.15 mM Ca2+. With Ca2+, simulated LVPes ("LVP"es) of ejecting contractions was significantly lower than isovolumic "LVP"es (-5.3 +/- 5.6%), whereas with Sr2+, ejecting "LVP"es was significantly higher than isovolumic "LVP"es (+4.5 +/- 7.5%). Contraction duration and time to end systole were markedly prolonged in ejecting vs. isovolumic contractions with either Ca2+ or Sr2+. As a consequence, comparison of simulated LVP between ejecting and isovolumic beats throughout the contraction, i.e., at the same simulated LVV and time, revealed only a positive effect of ejection with either Ca2+ (+18.8 +/- 5.5%) or Sr2+ (+23.4 +/-9.3%). We conclude that both positive and negative effects of ejection are basic myocardial properties.

Sign in / Sign up

Export Citation Format

Share Document