Propranolol-vagal-alveolar CO2 interactions on collateral gas flow in dog lungs

1982 ◽  
Vol 52 (6) ◽  
pp. 1426-1431 ◽  
Author(s):  
L. E. Olson ◽  
N. E. Robinson
Keyword(s):  
Gas Flow ◽  
Vagal Stimulation ◽  
High Co2 ◽  
Low Co2 ◽  
Co2 Levels ◽  
Lung Segment ◽  
Airway Opening ◽  
Residual Capacity ◽  
Propranolol Treatment ◽  
End Tidal

The mechanical properties of a collaterally ventilating lung segment were studied in 18 anesthetized paralyzed mongrel dogs artificially ventilated with room air end-tidal CO2 fraction = 5%. Nine dogs were pretreated with propranolol, and nine dogs were not. With 0, 5, or 12% CO2 in O2 flowing into the segment, steady-state resistance of segmental airways (Rss) and time for 90% pressure equilibration (T90) between the segment and airway opening after flow was discontinued were determined at functional residual capacity with the vagus nerve ipsilateral to the segment intact, sectioned, or electrically stimulated. Vagal stimulation increased Rss and T90 at all CO2 levels, whereas unilateral vagotomy had no effect. Propranolol treatment enhanced the increase in Rss caused by vagal stimulation at low but not at high CO2 levels, suggesting that high CO2 mimics the effect of propranolol on Rss. High levels of CO2 did not have the same effect as propranolol on T90, propranolol treatment reducing the increase in T90 caused by vagal stimulation at high but not at low CO2 levels. These results demonstrate that local changes in alveolar CO2 tensions modify but do not abolish the effect of vagal stimulation on collateral ventilation.

Effect of transpulmonary and driving pressures on collateral gas flow in dog lungs

1985 ◽  
Vol 59 (6) ◽  
pp. 1757-1765 ◽  
Author(s):  
L. E. Olson
Keyword(s):  
Gas Flow ◽  
Dynamic Pressure ◽  
Opening Pressure ◽  
Lung Segment ◽  
Peripheral Airway ◽  
Airway Opening ◽  
Residual Capacity ◽  
Collateral Pathways ◽  
Flow Through ◽  
Flow Pathways

The effect of changing segment pressure (Ps) and airway opening pressure (Pao) on flow through a collaterally ventilating lung segment was evaluated in intact and excised dog lungs. He, N2, and SF6 were passed through the lung segment distal to a catheter wedged in a peripheral airway at driving pressures (Ps - Pao) between 0.25 and 2 cm H2O. Eight excised caudal lobes were studied at Pao = 5, 10, and 15 cm H2O. Flow was directly related to Ps - Pao and Pao and inversely related to the density of the gas. A dimensionless plot of the driving pressure normalized to a reference dynamic pressure as a function of Reynolds number (Re) indicated that flow through the segment behaved as if it were laminar at Re less than 100 and that increasing Pao increased the dimension of the pathways conducting flow as shown previously. Small changes in Ps had no effect on pathway geometry or on the pattern of flow through the segment at Pao = 10 and 15 cmH2O. At Pao = 5 cm H2O increasing segment pressure appeared to increase the dimensions of the flow pathways slightly. Similar changes in Ps - Pao had no consistent effect on flow pattern or pathway geometry in six anesthetized, paralyzed, vagotomized dogs at functional residual capacity or after widely opening the chest (Pao = 5 cm H2O). These results suggest that, at large lobe volumes, airways (including collateral pathways) are maximally dilated and therefore relatively insensitive to small changes in segment pressure.

scholarly journals Photoprotection is regulated by light-independent CO2 availability

2021 ◽  
Author(s):  
M. Águila Ruiz-Sola ◽  
Serena Flori ◽  
Yizhong Yuan ◽  
Gaelle Villain ◽  
Emanuel Sanz-Luque ◽  
...  
Keyword(s):  
Chlamydomonas Reinhardtii ◽  
Green Alga ◽  
Total Darkness ◽  
Transcript Accumulation ◽  
High Co2 ◽  
Co2 Concentrating Mechanism ◽  
Low Co2 ◽  
Co2 Levels ◽  
Excess Light ◽  
The Impact

Photosynthetic algae cope with suboptimal levels of light and CO2. In low CO2 and excess light, the green alga Chlamydomonas reinhardtii activates a CO2 Concentrating Mechanism (CCM) and photoprotection; the latter is mediated by LHCSR1/3 and PSBS. How light and CO2 signals converge to regulate photoprotective responses remains unclear. Here we show that excess light activates expression of photoprotective and CCM-related genes and that depletion of CO2 drives these responses, even in total darkness. High CO2 levels, derived from respiration or impaired photosynthetic fixation, repress LHCSR3 and CCM genes while stabilizing the LHCSR1 protein. We also show that CIA5, which controls CCM genes, is a major regulator of photoprotection, elevating LHCSR3 and PSBS transcript accumulation while inhibiting LHCSR1 accumulation. Our work emphasizes the importance of CO2 in regulating photoprotection and the CCM, demonstrating that the impact of light on photoprotection is often indirect and reflects intracellular CO2 levels.

Effect of flow direction on collateral ventilation in excised dog lung lobes

1986 ◽  
Vol 60 (3) ◽  
pp. 770-776 ◽  
Author(s):  
L. E. Olson ◽  
P. A. Socha
Keyword(s):  
Gas Flow ◽  
Flow Direction ◽  
Order Effect ◽  
Driving Pressure ◽  
Lung Segment ◽  
Peripheral Airway ◽  
Airway Opening ◽  
Collateral Pathways ◽  
Flow Pathways ◽  
Lung Lobes

We determined the effect of flow direction on the relationship between driving pressure and gas flow through a collaterally ventilating lung segment in excised cranial and caudal dog lung lobes. He, N2, and SF6 were passed through the lung segment distal to a catheter wedged in a peripheral airway. Gases were pushed through the segment by raising segment pressure (Ps) relative to airway opening pressure (Pao) and pulled from the segment by ventilating the lobe with the test gas, then lowering Ps relative to Pao. Driving pressures (Ps - Pao) between 0.25 and 2 cmH2O were evaluated at Pao values of 5, 10, and 15 cmH2O. Results were similar in cranial and caudal lobes. Flow increased as Ps - Pao increased and was greatest at Pao = 15 cmH2O for the least-dense gas (He). Although flow direction was not a significant first-order effect, there was significant interaction between volume, driving pressure, and flow direction. Dimensional analysis suggested that, although flow direction had no effect at Pao = 10 and 15 cmH2O, at Pao = 5 cmH2O, raising Ps relative to Pao increased the characteristic dimension of the flow pathways, and reducing Ps relative to Pao reduced the dimension. These data suggest that at large lobe volumes, airways (including collateral pathways) within the segment are maximally dilated and the stiffness of the parenchyma prevents any significant distortion when Ps is altered. At low lobe volumes, these pathways are affected by changes in transmural pressure due to the increased airway and parenchymal compliance.

Pressure-flow relationships in a collaterally ventilating dog lung segment

1983 ◽  
Vol 54 (4) ◽  
pp. 956-960 ◽  
Author(s):  
L. E. Olson ◽  
J. R. Rodarte ◽  
N. E. Robinson
Keyword(s):  
Reynolds Number ◽  
Lung Volume ◽  
Dynamic Pressure ◽  
Reynolds Numbers ◽  
Pressure Losses ◽  
Lung Segment ◽  
Peripheral Airway ◽  
Airway Opening ◽  
Residual Capacity ◽  
Flow Through

We evaluated the pressure (P)-flow (V) relationship in collaterally ventilating dog lung segments by passing He, N2, and SF6 through a bronchoscope (5 mm OD) wedged in a peripheral airway. Measurements were made at functional residual capacity (FRC) and two higher lung volumes, keeping segment-to-airway opening pressure constant (3 cmH2O) in five anesthetized, paralyzed, vagotomized, supine dogs. Average flows ranged from 5.0 to 8.0 ml/s for He, 4.5 to 7.5 ml/s for N2, and 3.4 to 4.7 ml/s for SF6. When these data were fitted as P = K1/3/3 mu V + K2 rho V2, density-dependent pressure losses were unimportant when He and N2 were used, suggesting laminar flow with these gases. A dimensionless plot of the total pressure drop relative to a reference dynamic pressure as a function of Reynolds number at the bronchoscope tip suggested that flow through the segment behaved as if it were laminar at Reynolds numbers less than 100. Furthermore, when the airway diameter used to compute the normalized pressure and Reynolds number was scaled as the cubic root of lung volume, curves for all three gases were superimposed, suggesting that the dimensions of intrasegmental/collateral airways scale as lung volume 1/3.

scholarly journals Physiological resilience of pink salmon to naturally occurring ocean acidification

2020 ◽  
Vol 8 (1) ◽  
Author(s):  
Andrea Y Frommel ◽  
Justin Carless ◽  
Brian P V Hunt ◽  
Colin J Brauner
Keyword(s):  
British Columbia ◽  
Elevated Co2 ◽  
Condition Factor ◽  
Pacific Salmon ◽  
Pink Salmon ◽  
Hypoxia Tolerance ◽  
High Co2 ◽  
The North ◽  
Naturally Occurring ◽  
Co2 Levels

Abstract Pacific salmon stocks are in decline with climate change named as a contributing factor. The North Pacific coast of British Columbia is characterized by strong temporal and spatial heterogeneity in ocean conditions with upwelling events elevating CO2 levels up to 10-fold those of pre-industrial global averages. Early life stages of pink salmon have been shown to be affected by these CO2 levels, and juveniles naturally migrate through regions of high CO2 during the energetically costly phase of smoltification. To investigate the physiological response of out-migrating wild juvenile pink salmon to these naturally occurring elevated CO2 levels, we captured fish in Georgia Strait, British Columbia and transported them to a marine lab (Hakai Institute, Quadra Island) where fish were exposed to one of three CO2 levels (850, 1500 and 2000 μatm CO2) for 2 weeks. At ½, 1 and 2 weeks of exposure, we measured their weight and length to calculate condition factor (Fulton’s K), as well as haematocrit and plasma [Cl−]. At each of these times, two additional stressors were imposed (hypoxia and temperature) to provide further insight into their physiological condition. Juvenile pink salmon were largely robust to elevated CO2 concentrations up to 2000 μatm CO2, with no mortality or change in condition factor over the 2-week exposure duration. After 1 week of exposure, temperature and hypoxia tolerance were significantly reduced in high CO2, an effect that did not persist to 2 weeks of exposure. Haematocrit was increased by 20% after 2 weeks in the CO2 treatments relative to the initial measurements, while plasma [Cl−] was not significantly different. Taken together, these data indicate that juvenile pink salmon are quite resilient to naturally occurring high CO2 levels during their ocean outmigration.

WRKY transcription factors in the response of table grapes (cv. Autumn Royal) to high CO2 levels and low temperature

2019 ◽  
Vol 150 ◽  
pp. 42-51 ◽  
Author(s):  
Irene Romero ◽  
Estibaliz Alegria-Carrasco ◽  
Alfonso Gonzalez de Pradena ◽  
Maria Vazquez-Hernandez ◽  
M. Isabel Escribano ◽  
...  
Keyword(s):  
Transcription Factors ◽  
Low Temperature ◽  
Wrky Transcription Factors ◽  
High Co2 ◽  
Table Grapes ◽  
Co2 Levels

Effects of the Water Content of Soda Lime on Compound A Concentration in the Anesthesia Circuit in Sevoflurane Anesthesia 

1998 ◽  
Vol 88 (1) ◽  
pp. 66-71 ◽  
Author(s):  
Hiromichi Bito ◽  
Yukako Ikeuchi ◽  
Kazuyuki Ikeda
Keyword(s):  
Gas Flow ◽  
Soda Lime ◽  
Absorption Capacity ◽  
Low Flow ◽  
Co2 Absorption ◽  
Sevoflurane Anesthesia ◽  
Compound A ◽  
Carbon Dioxide Co2 ◽  
End Tidal ◽  
Co2 Elimination

Background Sevoflurane anesthesia is usually performed with fresh gas flow rates greater than 2 l/min due to the toxicity of compound A in rats and limited clinical experience with sevoflurane in low-flow systems. However, to reduce costs, it would be useful to identify ways to reduce compound A concentrations in low-flow sevoflurane anesthesia. This goal of this study was to determine if compound A concentrations can be reduced by using soda lime with water added. Methods Low-flow sevoflurane anesthesia (fresh gas flow of 1 l/min) was performed in 37 patients using soda lime with water added (perhydrated soda lime) or standard soda lime as the carbon dioxide (CO2) absorbent. The soda lime was not changed between patients, but rather was used until CO2 rebreathing occurred. The perhydrated soda lime was prepared by spraying 100 ml distilled water onto 1 kg fresh soda lime, and water was added only when a new bag of soda lime was placed into the canister. Compound A concentrations in the circle system, soda lime temperatures, inspired and end-tidal CO2 and end-tidal sevoflurane concentrations, and CO2 elimination by the patient were measured during anesthesia. Results Compound A concentrations were significantly lower for the perhydrated soda lime (1.9 +/- 1.8 ppm; means +/- SD) than for the standard soda lime (13.9 +/- 8.2 ppm). No differences were seen between the two types of soda lime with regard to the temperature of the soda lime, end-tidal sevoflurane concentrations, or CO2 elimination. Compound A concentration decreased with the total time of soda lime use for both types of soda lime. The CO2 absorption capacity was significantly less for perhydrated soda lime than for standard soda lime. Conclusions Compound A concentrations in the circuit can be reduced by using soda lime with water added. The CO2 absorption capacity of the soda lime is reduced by adding water to it, but this should not be clinically significant.

Effect of Fresh Gas Flow on Isoflurane Concentrations during Low-flow Anaesthesia

2005 ◽  
Vol 33 (5) ◽  
pp. 513-519 ◽  
Author(s):  
J-Y Park ◽  
J-H Kim ◽  
W-Y Kim ◽  
M-S Chang ◽  
J-Y Kim ◽  
...  
Keyword(s):  
Gas Flow ◽  
Low Flow ◽  
Physical Status ◽  
Closed Circle ◽  
Haemodynamic Changes ◽  
Low Flow Anaesthesia ◽  
Baseline Values ◽  
American Society ◽  
End Tidal ◽  
Closed Circle System

The effect of fresh gas flow (FGF) on isoflurane concentrations at given vaporizer settings during low-flow anaesthesia was investigated. Ninety patients (American Society of Anaesthesiologists physical status I or II) were randomly allocated to three groups (FGF 1 l/min, FGF 2 l/min and FGF 4 l/min). Anaesthesia was maintained for 10 min with vaporizer setting isoflurane 2 vol% and FGF 4 l/min for full-tissue anaesthetic uptake in a semi-closed circle system. Low-flow anaesthesia was maintained for 20 min with end-tidal isoflurane 1.5 vol% and FGF 2 l/min. FGF was then changed to FGF 1 l/min, FGF 2 l/min or FGF 4 l/min. Measurements during the 20-min period showed that inspired and end-tidal isoflurane concentrations decreased in the FGF 1-l/min group but increased in the FGF 4-l/min group compared with baseline values. No haemodynamic changes were observed. Monitoring of anaesthetic concentrations and appropriate control of vaporizer settings are necessary during low-flow anaesthesia.

Sign in / Sign up

Export Citation Format

Share Document