Rapidly adapting receptor activity in dogs is inversely related to lung compliance

1986 ◽  
Vol 61 (5) ◽  
pp. 1980-1987 ◽  
Author(s):  
A. Jonzon ◽  
T. E. Pisarri ◽  
J. C. Coleridge ◽  
H. M. Coleridge
Keyword(s):  
Inflation Rate ◽  
Impulse Activity ◽  
Lung Compliance ◽  
Excitatory Input ◽  
Rate Of Change ◽  
Positive End Expiratory Pressure ◽  
Vagus Nerves ◽  
Constant Rate ◽  
Length Constant ◽  
Dynamic Lung Compliance

We examined the response of pulmonary rapidly adapting receptors (RAR′s) to changes in dynamic lung compliance (Cdyn) in the physiological range. RAR impulse activity was recorded from the cervical vagus nerves in anesthetized open-chest dogs whose lungs were ventilated at constant rate and tidal volume (VT), with a positive end-expiratory pressure (PEEP) of 3–4 cmH2O. After hyperinflation to produce maximal Cdyn, RAR′s were silent or fired sparsely and irregularly. Reducing Cdyn in steps by briefly removing PEEP increased firing proportionately, and RAR′s began to discharge vigorously in inflation. Activity was restored to control by hyperinflating the lungs. Activity also increased when we increased inflation rate, and hence the rate of change of airway pressure (dP/dt), by reducing inflation time, keeping VT and cycle length constant. RAR′s were stimulated more when dP/dt was increased by reducing compliance than when dP/dt was increased by increasing inflation rate. We conclude that RAR′s are sensitive to changes in Cdyn and speculate that excitatory input from RAR′s may help to maintain VT as the lungs become stiffer.

scholarly journals Changes in dynamic lung mechanics after lung volume reduction coil treatment of severe emphysema

Thorax ◽  
2017 ◽  
Vol 73 (6) ◽  
pp. 584-586 ◽  
Author(s):  
Demosthenes Makris ◽  
Sylvie Leroy ◽  
Johana Pradelli ◽  
Jonathan Benzaquen ◽  
Hervé Guenard ◽  
...  
Keyword(s):  
Lung Volume ◽  
Lung Compliance ◽  
Lung Mechanics ◽  
Dynamic Hyperinflation ◽  
Positive End Expiratory Pressure ◽  
Lung Volume Reduction ◽  
Inspiratory Capacity ◽  
Endurance Time ◽  
Significant Attenuation ◽  
Dynamic Lung Compliance

We assessed the relationships between changes in lung compliance, lung volumes and dynamic hyperinflation in patients with emphysema who underwent bronchoscopic treatment with nitinol coils (coil treatment) (n=11) or received usual care (UC) (n=11). Compared with UC, coil treatment resulted in decreased dynamic lung compliance (CLdyn) (p=0.03) and increased endurance time (p=0.010). The change in CLdyn was associated with significant improvement in FEV1 and FVC, with reduction in residual volume and intrinsic positive end-expiratory pressure, and with increased inspiratory capacity at rest/and at exercise. The increase in end-expiratory lung volume (EELV) during exercise (EELVdyn-ch=EELVisotime EELVrest) demonstrated significant attenuation after coil treatment (p=0.02).

Rapidly adapting receptors monitor lung compliance in spontaneously breathing dogs

1990 ◽  
Vol 68 (5) ◽  
pp. 1997-2005 ◽  
Author(s):  
T. E. Pisarri ◽  
A. Jonzon ◽  
J. C. Coleridge ◽  
H. M. Coleridge
Keyword(s):  
Tidal Volume ◽  
Spontaneous Breathing ◽  
Transpulmonary Pressure ◽  
Lung Compliance ◽  
Vagus Nerves ◽  
Concomitant Increase ◽  
Inflatable Cuff ◽  
Lung Expansion ◽  
Dynamic Lung Compliance ◽  
Spontaneously Breathing

We examined the ability of rapidly adapting receptors (RARs) to monitor changes in dynamic lung compliance (Cdyn) in anesthetized spontaneously breathing dogs by recording RAR impulses from the vagus nerves. We decreased Cdyn in steps through the physiological range by briefly restricting lung expansion with an inflatable cuff around the chest and recording the response after deflating the cuff; we restored Cdyn to control by hyperinflating the lungs. Of 45 RARs, 34 were stimulated by a 40 +/- 2% reduction in Cdyn, their inspiratory discharge increasing on average more than threefold. Two-thirds of responsive RARs were stimulated by less than or equal to 20% reductions in Cdyn; in most, firing increased proportionately with lung stiffness (1/Cdyn) as Cdyn was decreased further. Stimulation by reduced Cdyn was not simply a function of the concomitant increase in transpulmonary pressure, because similar increases in pressure produced by increasing tidal volume produced smaller increases in firing. RAR stimulation was unaffected by atropine and, hence, was not dependent on neurally mediated changes in bronchomotor tone. Our results indicate that during spontaneous breathing RARs provide a signal inversely proportional to Cdyn.

LUNG FUNCTION AND PATHOLOGY IN A PREMATURE INFANT WITH CHRONIC PULMONARY INSUFFICIENCY (WILSON-MIKITY SYNDROME)

PEDIATRICS ◽  
1967 ◽  
Vol 40 (6) ◽  
pp. 962-974
Author(s):  
W. A. Aherne ◽  
K. W. Cross ◽  
E. N. Hey ◽  
Sheila R. Lewis
Keyword(s):  
Lung Function ◽  
Premature Infant ◽  
Lung Biopsy ◽  
Signs And Symptoms ◽  
Lung Compliance ◽  
Alveolar Ventilation ◽  
Pulmonary Insufficiency ◽  
Normal Limits ◽  
Dynamic Lung Compliance ◽  
Symptoms And Signs

Detailed lung function studies at the age of 8 months and 1 year are reported for an infant who weighed 992 gm at birth and who developed chronic progressive pulmonary insufficiency 2 weeks after birth. The symptoms and signs were similar to those described by Wilson and Mikity in 1960. A confirmatory lung biopsy was obtained when the child was 11 months old. Dynamic lung "compliance" was very significantly reduced while a static estimate of lung compliance was within normal limits. These and other lung function findings are interpreted as indicating that uneven alveolar ventilation was the probable functional basis for all the signs and symptoms observed.

Fast-phase transvascular fluid flux and the Fahraeus effect

1987 ◽  
Vol 62 (4) ◽  
pp. 1513-1520 ◽  
Author(s):  
W. N. Richardson ◽  
D. Bilan ◽  
M. Hoppensack ◽  
L. Oppenheimer
Keyword(s):  
Mechanical Properties ◽  
Slow Rate ◽  
Time Course ◽  
Rate Of Change ◽  
Distributed Model ◽  
Slow Phase ◽  
Fluid Flux ◽  
Fast Phase ◽  
Constant Rate ◽  
Fahraeus Effect

Transvascular fluid flux was induced in six isolated blood-perfused canine lobes by increasing and decreasing hydrostatic inflow pressure (Pi). Fluid flux was followed against the change in concentration of an impermeable tracer (Blue Dextran) measured directly with a colorimetric device. The time course of fluid flux was biphasic with an initial fast transient followed by a slow phase. Hematocrit changes unrelated to fluid flux occurred due to the Fahraeus effect, and their contribution to the total color signal was subtracted to determine the rate of fast fluid flux (Qf). Qf was related to Pi to derive fast-phase conductance (Kf). Slow-phase Kf was calculated from the constant rate of change of lobe weight. For a mean change in Pi of 7 cmH2O, 40% of the color signal was due to fluid flux. Fast- and slow-phase Kf's were 0.86 +/- 0.15 and 0.27 +/- 0.05 ml X min-1. cmH2O–1 X 100 g dry wt-1. The fast-phase Kf is smaller than that reported for plasma-perfused lobes. Possible explanations discussed are the nature of the perfusate, the mechanical properties of the interstitium, and the slow rate of rise of the driving pressure at the filtration site on the basis of a distributed model of pulmonary vascular compliance.

Dynamic lung compliance in newborn and adult cats

1986 ◽  
Vol 60 (3) ◽  
pp. 743-750 ◽  
Author(s):  
K. J. Sullivan ◽  
J. P. Mortola
Keyword(s):  
Stress Relaxation ◽  
Transpulmonary Pressure ◽  
Lung Compliance ◽  
Theoretical Treatment ◽  
The Difference ◽  
Adult Cats ◽  
Isolated Lungs ◽  
Dynamic Lung Compliance ◽  
Volume History ◽  
Lung Stress

Static (Cstat) and dynamic (Cdyn) lung compliance and lung stress relaxation were examined in isolated lungs of newborn kittens and adult cats. Cstat was determined by increasing volume in increments and recording the corresponding change in pressure; Cdyn was calculated as the ratio of the changes in volume to transpulmonary pressure between points of zero flow at ventilation frequencies between 10 and 110 cycles/min. Lung volume history, end-inflation volume, and end-deflation pressure were maintained constant. At the lowest frequency of ventilation, Cdyn was less than Cstat, the difference being greater in newborns. Between 20 and 100 cycles/min, Cdyn of the newborn lung remained constant, whereas Cdyn of the adult lung decreased after 60 cycles/min. At all frequencies, the rate of stress relaxation, measured as the decay in transpulmonary pressure during maintained inflation, was greater in newborns than in adults. The frequency response of Cdyn in kittens, together with the relatively greater rate of stress relaxation, suggests that viscoelasticity contributes more to the dynamic stiffening of the lung in newborns than in adults. A theoretical treatment of the data based on a linear model of viscoelasticity supports this conclusion.

Lung dysfunction after thermal injury in relation to prostanoid and oxygen radical release

1986 ◽  
Vol 61 (1) ◽  
pp. 103-112 ◽  
Author(s):  
L. J. Jin ◽  
C. Lalonde ◽  
R. H. Demling
Keyword(s):  
Lipid Peroxidation ◽  
Lung Tissue ◽  
Lipid Peroxide ◽  
Lung Compliance ◽  
Base Line ◽  
Lung Water ◽  
Control Value ◽  
Lung Dysfunction ◽  
Dynamic Lung Compliance ◽  
Lung Lymph

We studied whether changes in lung function after burns (1- to 12-h period) were due to changes in lung water or airways resistance and the relationship of the changes to prostanoid and O2 radical activity (measured as lipid peroxidation). Twenty-five anesthetized mechanically ventilated adult sheep were given a 40% of body surface scald burn and resuscitated to restore and maintain base-line filling pressures. Dynamic lung compliance (Cdyn) decreased by 40% from 38 +/- 5 to 24 +/- 4 ml/cmH2O at 12 h. Venous thromboxane B2 transiently increased from 210 +/- 40 to 1,100 +/- 210 pg/ml, and the value in lung lymph increased from 180 +/- 80 to 520 +/- 80 pg/ml. Prostacyclin levels in lung lymph and plasma remained at base line. Protein-poor lung lymph flow increased two- to threefold, but postmortem lung analysis revealed no increase in lung water from the control of 3.5 +/- 0.3 g H2O/g dry wt. No increase in protein permeability was seen. However, the lipid peroxidation of lung tissue measured as malondialdehyde was significantly increased from the control value of 56 +/- 4 nmol/g lung to a value of 69 +/- 6. Ibuprofen pretreatment (12.5 mg/kg) markedly attenuated the decrease in Cdyn, with the value at 12 h being 90% of base line. Ibuprofen also decreased the amount of lung lipid peroxidation but did not decrease the lung lymph response. We conclude that the decrease in Cdyn seen early postburn is not due to increased lung water, but, rather, is due to a mediator-induced bronchoconstriction, attenuated by ibuprofen; the mediator being either thromboxane or a byproduct of O2 radicals as evidenced by increased lipid peroxide production in lung tissue.

Origin and Geomorphology

2006 ◽  
Author(s):  
Thomas S. Bianchi
Keyword(s):  
Sea Level ◽  
Rate Of Change ◽  
Interglacial Period ◽  
Continental Margins ◽  
Before Present ◽  
Sea Level Changes ◽  
The Past ◽  
Constant Rate ◽  
Geologic Record ◽  
The U.S

Geologically speaking, estuaries are ephemeral features of the coasts. Upon formation, most begin to fill in with sediments and, in the absence of sea level changes, would have life spans of only a few thousand to tens of thousands of years (Emery and Uchupi, 1972; Schubel, 1972; Schubel and Hirschberg, 1978). Estuaries have been part of the geologic record for at least the past 200 million years (My) BP (before present; Williams, 1960; Clauzon, 1973). However, modern estuaries are recent features that only formed over the past 5000 to 6000 years during the stable interglacial period of the middle to late Holocene epoch (0–10,000 y BP), which followed an extensive rise in sea level at the end of the Pleistocene epoch (1.8 My to 10,000 y BP; Nichols and Biggs, 1985). There is general agreement that four major glaciation to interglacial periods occurred during the Pleistocene. It has been suggested that sea level was reduced from a maximum of about 80 m above sea level during the Aftoninan interglacial to 100 m below sea level during the Wisconsin, some 15,000 to 18,000 y BP (figure 2.1; Fairbridge, 1961). This lowest sea level phase is referred to as low stand and is usually determined by uncovering the oldest drowned shorelines along continental margins (Davis, 1985, 1996); conversely, the highest sea level phase is referred to as high stand. It is generally accepted that low-stand depth is between 130 and 150 m below present sea level and that sea level rose at a fairly constant rate until about 6000 to 7000 y BP (Belknap and Kraft, 1977). A sea level rise of approximately 10 mm y−1 during this period resulted in many coastal plains being inundated with water and a displacement of the shoreline. The phenomenon of rising (transgression) and falling (regression) sea level over time is referred to as eustacy (Suess, 1906). When examining a simplified sea level curve, we find that the rate of change during the Holocene is fairly representative of the Gulf of Mexico and much of the U.S. Atlantic coastline (Curray, 1965).

Effects of decreasing lung compliance with oleic acid on the cardiovascular response to PEEP

1977 ◽  
Vol 233 (6) ◽  
pp. H635-H641 ◽  
Author(s):  
S. M. Scharf ◽  
R. H. Ingram
Keyword(s):  
Oleic Acid ◽  
Venous Return ◽  
Cardiovascular Response ◽  
Lung Compliance ◽  
Back Pressure ◽  
Right Atrial ◽  
Positive End Expiratory Pressure ◽  
Chest Wall Compliance ◽  
Before And After ◽  
Wall Compliance

In 12 anesthetized mongrel dogs on a constant volume ventilator, the response of the cardiovascular system to increasing positive end-expiratory pressure (PEEP) was examined before and after inducing acute lung injury with oleic acid. As PEEP was raised to approximately 16 mmHg, lung volume increased by approximately 900 ml before oleic acid and only 350 ml after. Pleural pressure increased by the same amount, indicating that both lung and chest wall compliance decreased with oleic acid. Right atrial pressure, the back pressure to venous return, also increased by the same amount. Although cardiac output at PEEP = 0 was lower after oleic acid, the relative decrements produced by increasing PEEP were the same as before oleic acid.

Nonadrenergic bronchodilation induced by high concentrations of sulfur dioxide

1990 ◽  
Vol 69 (5) ◽  
pp. 1786-1791
Author(s):  
D. C. Thompson ◽  
J. L. Szarek ◽  
R. J. Altiere ◽  
L. Diamond
Keyword(s):  
Muscle Tone ◽  
Blocking Agent ◽  
Lung Compliance ◽  
Environmental Pollutant ◽  
Inhibitory System ◽  
Experimental Conditions ◽  
Bronchodilator Response ◽  
Cellular Source ◽  
High Concentrations ◽  
Dynamic Lung Compliance

SO2 is an environmental pollutant known to elicit bronchospasm in susceptible subjects. We observed that brief exposure of artificially bronchoconstricted cats to high concentrations of SO2 induces a bronchodilator response. This study assessed the characteristics of this response and examined various mechanisms that might underlie it. Cats were anesthetized with diallylbarbital-urethan, and airway smooth muscle tone, measured by lung resistance and dynamic lung compliance, was elevated with a continuous infusion of 5-hydroxytryptamine. Administration of 10 breaths of SO2 via a tracheostomy induced concentration-dependent bronchodilation in the range 100-1,000 parts/million. Only infrequently was bronchoconstriction observed before bronchodilation. SO2-induced bronchodilator responses were unaffected by pretreatment with intravenous atropine or propranolol, establishing them as nonadrenergic noncholinergic (NANC) in origin. Neither the ganglionic blocking agent hexamethonium nor the nerve toxin tetrodotoxin influenced the SO2-induced bronchodilation, thus excluding a role for central or local autonomic reflexes in the response. Efforts to modulate the response by pretreatment with the cyclooxygenase inhibitor indomethacin or the mediator release inhibitor cromolyn sodium also were unsuccessful. Administration of acidic aerosols failed to mimic the SO2-induced bronchodilator response. Although the mechanism whereby SO2 induces bronchodilation under these experimental conditions remains unclear, release of a NANC inhibitory transmitter from a neural, epithelial, or other cellular source via a mechanism insensitive to both tetrodotoxin and cromolyn is a distinct possibility. An intrinsic NANC inhibitory system may exist in feline airways functioning as a local regulator of bronchomotor tone and possibly serving to override responses to strong, potentially asphyxial bronchoconstrictive stimuli.

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