Rate of Gas Exchange in the Middle Ear of Guinea Pigs

1998 ◽  
Vol 107 (3) ◽  
pp. 194-198 ◽  
Author(s):  
Haya Mover-Lev ◽  
Jacob Sadé ◽  
Amos Ar
Keyword(s):  
Gas Exchange ◽  
Middle Ear ◽  
Guinea Pigs ◽  
Blood Perfusion ◽  
Limiting Factors ◽  
Physiological Mechanisms ◽  
Diffusion Limited ◽  
Carbon Dioxide Co2 ◽  
Rate Ratios ◽  
Limited Process

Gas exchange between blood in the middle ear (ME) mucosa and ambient ME gas may be limited by diffusion through tissue or blood perfusion. In order to study the limiting factors in ME gas exchange, a hole was drilled in the bulla of 14 anesthetized guinea pigs through which a mass spectrometer probe was inserted and sealed in place. The rate at which oxygen (O2), carbon dioxide (CO2), nitrogen, and argon concentrations changed toward their steady state values was recorded. From the exponential fitted curves, gas rate constants (Kg) were calculated. The ratio KCO2/KO2 was 4:1, which is lower than expected from a diffusion-limited process in an aqueous compartment. The different rate ratios of CO2 and O2 indicate a diffusion-limited process. However, the deviation of the KCO2/KO2 ratio from that expected in aqueous solutions may indicate the involvement of a lipid compartment in gas exchange or other physiological mechanisms such as local acidity.

Middle Ear Gas Exchange in Rhesus Monkeys

1994 ◽  
Vol 103 (8) ◽  
pp. 636-645 ◽  
Author(s):  
William J. Doyle ◽  
James T. Seroky
Keyword(s):  
Carbon Dioxide ◽  
Gas Exchange ◽  
Middle Ear ◽  
Rate Constants ◽  
Rhesus Monkeys ◽  
Data Rate ◽  
Diffusion Limited ◽  
Middle Ear Pressure ◽  
Carbon Dioxide Co2 ◽  
Limited Process

The mechanism of gas exchange between the middle ear and tissue is fundamental to understanding middle ear physiology and pathophysiology. In this study, the middle ears of six rhesus monkeys were inflated on separate occasions with nitrogen (N2), carbon dioxide (CO2), and oxygen (O2), and middle ear pressures were recorded at defined times postinflation for up to 4 hours. From these data, rate constants governing the exchange of these gases were estimated and compared to those predicted under both diffusion and perfusion limitations. The results show that the rate constants for middle ear to tissue exchange of O2 and CO2 are consistent with a diffusion-limited process. In contrast, middle ear pressure did not decrease over the study period following introduction of N2 into the middle ear. This is interpretable as a much slower rate of N2 exchange than that predicted by either perfusion or diffusion-limited models calibrated to the O2 and CO2 rate constants. These results have significant implications for middle ear gas exchange and suggest that for relatively short observation periods, the behavior of middle ear pressure is controlled by experimentally established O2 and CO2 gradients.

scholarly journals Oxygen-Sensitivity and Pulmonary Selectivity of Vasodilators as Potential Drugs for Pulmonary Hypertension

Antioxidants ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 155
Author(s):  
Daniel Morales-Cano ◽  
Bianca Barreira ◽  
Beatriz De Olaiz Navarro ◽  
María Callejo ◽  
Gema Mondejar-Parreño ◽  
...  
Keyword(s):  
Pulmonary Hypertension ◽  
Gas Exchange ◽  
Pulmonary Circulation ◽  
Pulmonary Arteries ◽  
Blood Perfusion ◽  
Mesenteric Arteries ◽  
Oxygen Sensitivity ◽  
Low Oxygen ◽  
Oxygen Selectivity

Current approved therapies for pulmonary hypertension (PH) aim to restore the balance between endothelial mediators in the pulmonary circulation. These drugs may exert vasodilator effects on poorly oxygenated vessels. This may lead to the derivation of blood perfusion towards low ventilated alveoli, i.e., producing ventilation-perfusion mismatch, with detrimental effects on gas exchange. The aim of this study is to analyze the oxygen-sensitivity in vitro of 25 drugs currently used or potentially useful for PH. Additionally, the study analyses the effectiveness of these vasodilators in the pulmonary vs. the systemic vessels. Vasodilator responses were recorded in pulmonary arteries (PA) and mesenteric arteries (MA) from rats and in human PA in a wire myograph under different oxygen concentrations. None of the studied drugs showed oxygen selectivity, being equally or more effective as vasodilators under conditions of low oxygen as compared to high oxygen levels. The drugs studied showed low pulmonary selectivity, being equally or more effective as vasodilators in systemic than in PA. A similar behavior was observed for the members within each drug family. In conclusion, none of the drugs showed optimal vasodilator profile, which may limit their therapeutic efficacy in PH.

Effect of topically applied povidone-iodine on transient evoked otoacoustic emissions in guinea pigs

2003 ◽  
Vol 117 (9) ◽  
pp. 700-703 ◽  
Author(s):  
Recep Yagiz ◽  
Abdullah Tas ◽  
Cem Uzun ◽  
Mustafa Kemal Adali ◽  
Muhsin Koten ◽  
...  
Keyword(s):  
Middle Ear ◽  
Guinea Pigs ◽  
Otoacoustic Emissions ◽  
Povidone Iodine ◽  
Positive Control ◽  
Middle Ear Surgery ◽  
Iodine Solution ◽  
Before And After ◽  
Transiently Evoked Otoacoustic Emissions ◽  
Povidone Iodine Solution

The possible cochlear toxicity of topically applied povidone-iodine solution was investigated in guinea pigs by measuring transiently evoked otoacoustic emissions (TEOAEs). Seven adult pigmented guinea pigs (14 ears) with a normal acoustic pinna reflex were used. After the baseline TEOAE measurements, 0.1mL of povidone-iodine solution was applied transtympanically into the middle ear in the study group. Saline solution and gentamicin were used as negative and positive control, respectively. TEOAE measurements were repeated on the 10th day, and four weeks after the first application. Tympanometric measurements were also carried out for both ears of all animals at the end of the study. Responses in all ears, which had povidone-iodine applied to them, disappeared in a way similar to those recorded in gentamicin-treated ears. Tympanometric measurements at the end of the study showed ’type A’ tympanograms in all ears of all animals. The present study showed that povidone-iodine could have a cochleotoxic effect in guinea pigs. A study in humans with TEOAE before and after middle-ear surgery, where povidone-iodine can reach into the middle-ear cavity, may be useful for evaluating this result for clinical practice.

scholarly journals Gas Exchange Function of the Middle Ear Mucosa in Patients with Cleft Palate.

1998 ◽  
Vol 91 (3) ◽  
pp. 227-231
Author(s):  
Makito TANABE ◽  
Haruo Takahashi ◽  
Iwao HONJI ◽  
Masaki SAWADA
Keyword(s):  
Gas Exchange ◽  
Cleft Palate ◽  
Middle Ear ◽  
Middle Ear Mucosa ◽  
Exchange Function

The Response to Human rIL-1, rIL-2, and rTNF in the Middle Ear of Guinea Pigs

1991 ◽  
Vol 101 (3) ◽  
pp. 271???275 ◽  
Author(s):  
Antonino Catanzaro ◽  
Allen Ryan ◽  
Sharon Batcher ◽  
Stephen I. Wasserman
Keyword(s):  
Middle Ear ◽  
Guinea Pigs

Middle ear gas exchange in isobaric counterdiffusion

1979 ◽  
Vol 47 (6) ◽  
pp. 1239-1244 ◽  
Author(s):  
C. W. Dueker ◽  
C. J. Lambertsen ◽  
J. J. Rosowski ◽  
J. C. Saunders
Keyword(s):  
Nitrous Oxide ◽  
Gas Exchange ◽  
Tympanic Membrane ◽  
Eustachian Tube ◽  
Middle Ear ◽  
Inert Gas ◽  
Pressure Measurements ◽  
Gas Sampling ◽  
Gas Space ◽  
Counter Diffusion

Nitrous oxide entry into the middle ear gas space was studied in cats in relation to anesthesia and the vestibular dysfunction caused by isobaric inert gas counter-diffusion in diving. A catheter implanted in the auditory bulla was used for direct gas sampling and pressure measurements. Experiments were designed to evaluate the participation of the eustachian tube, mucosal blood vessels, and tympanic membrane in middle ear gas exchange. The eustachian tube did not contribute to N2O entry and the mucosal blood supply only contributed about one-third of the total N2O accumulation. Diffusion across the tympanic membrane accounted for most of the N2O entering the middle ear from ambient and respiratory environments containing N2O.

scholarly journals Hydrogen desorption in SiGe films: A diffusion limited process

1997 ◽  
Vol 70 (24) ◽  
pp. 3287-3289 ◽  
Author(s):  
J. Vizoso ◽  
F. Martín ◽  
J. Suñé ◽  
M. Nafría
Keyword(s):  
Hydrogen Desorption ◽  
Diffusion Limited ◽  
Limited Process

Immunofluorescent Study on Middle Ear Mucosa

1980 ◽  
Vol 89 (3_suppl) ◽  
pp. 333-338 ◽  
Author(s):  
Goro Mogi ◽  
Shoichi Maeda ◽  
Noritake Watanabe
Keyword(s):  
Middle Ear ◽  
Guinea Pigs ◽  
Secretory Component ◽  
Direct Immunofluorescence ◽  
Secretory Proteins ◽  
Tympanic Cavity ◽  
Defense System ◽  
Middle Ear Mucosa ◽  
Local Synthesis ◽  
Immunofluorescent Study

To clarify the developmental course of the immunological defense system in the middle ear, immunoglobulin-forming cells of different classes and secretory proteins, such as secretory component (SC) and lactoferrin (Lf), were investigated in the middle ear mucosa of 20 developing and 5 normal adult guinea pigs by use of direct immunofluorescence technique. Changes in the middle ear mucosa were also observed after antigenic challenges directly to the tympanic cavity of 6 developing and 39 adult guinea pigs. IgA- and IgM-forming cells began to appear in the tubal mucosa at the seventh postnatal day, while it was scarcely possible to find IgG1- and IgG2-forming cells in developing guinea pigs. Immunoglobulin-forming cells of all classes increased in the middle ear mucosa after the antigenic stimuli. The injection of antigens to the tympanic cavity of developing animals induced the most striking accumulation of immunoglobulin-forming cells in the middle ear mucosa. Results of this study showed that local synthesis of IgA, as well as other classes, is latent in the middle ear, that the middle ear of immature animals is vulnerable to antigenic stimuli, and that the middle ear of developing animals possesses potential immune responsiveness.

scholarly journals PHYSIOLOGICAL RESPONSES OF THREE WOODY SPECIES SEEDLINGS UNDER WATER STRESS, IN SOIL WITH AND WITHOUT ORGANIC MATTER

2016 ◽  
Vol 40 (3) ◽  
pp. 455-464 ◽  
Author(s):  
Maria da Assunção Machado Rocha ◽  
Claudivan Feitosa de Lacerda ◽  
Marlos Alves Bezerra ◽  
Francisca Edineide Lima Barbosa ◽  
Hernandes de Oliveira Feitosa ◽  
...  
Keyword(s):  
Organic Matter ◽  
Water Stress ◽  
Gas Exchange ◽  
Leaf Gas Exchange ◽  
Water Status ◽  
Near Field ◽  
Limiting Factors ◽  
Water Restriction ◽  
Soil Water Retention ◽  
African Mahogany

ABSTRACT The low availability of water in the soil is one of the limiting factors for the growth and survival of plants. The objective of this study was to evaluate the responses of physiological processes in early growth of guanandi (Calophyllum brasilense Cambess), African mahogany (Khayai vorensis A. Chev) and oiti (Licaniato mentosa Benth Fritsch) over a period of water stress and other of rehydration in the soil with and without addition of organic matter. The study was conducted in a greenhouse and the experimental design was completely randomised into a 3 x 2 x 2 factorial scheme, comprising three species (guanandi, African mahogany, and oiti), two water regimes (with and without water restriction) and two levels of organic fertilisation (with and without the addition of organic matter). Irrigation was suspended for 15 days in half of the plants, while the other half (control) continued to receive daily irrigation, the soil being maintained near field capacity for these plants. At the end of the stress period, the plants were again irrigated for 15 days to determine their recovery. Water restriction reduced leaf water potential and gas exchange in the three species under study, more severely in soil with no addition of organic matter. The addition of this input increased soil water retention and availability to the plants during the suspension of irrigation, reducing the detrimental effects of the stress. During the period of rehydration, there was strong recovery of water status and leaf gas exchange. However recovery was not complete, suggesting that some of the effects caused by stress irreversibly affected cell structures and functions. However, of the species being studied, African mahogany displayed a greater sensitivity to stress, with poorer recovery.

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