Please use this identifier to cite or link to this item: https://hdl.handle.net/11499/5538
Title: The effects of changing middle ear pressure and gas partial pressure on mucosal blood flow and vascular permeability in the chinchilla
Authors: Alper, C.M.
Ardıç, Fazıl Necdet
Doyle, W.J.
Keywords: Chincilla
Middle ear pressure
Mucosal blood flow
animal experiment
animal model
animal tissue
article
blood vessel permeability
capillary
carbon dioxide tension
chinchilla
controlled study
effusion
middle ear
middle ear pressure
mucosa
nonhuman
oxygen tension
Animals
Capillary Permeability
Chinchilla
Ear, Middle
Gases
Mucous Membrane
Partial Pressure
Pressure
Abstract: Objective: To determine if middle ear (ME) gas composition and/or total pressure regulates local mucosal blood flow (MBF) and vascular permeability. The hypotheses tested are: (1) relatively high local CO 2 tensions and/or low O 2 tensions increase the ME MBF and vascular permeability; and (2) sub- atmospheric total ME pressure provokes similar effects. Methods: The responses of ME MBF and vascular permeability parameters were measured during 60 min exposures of chinchilla MEs to one of two test gas mixtures (16.3% O 2 , 5.1% CO 2 , balance N 2 , or 5.3% O 2 , 15.6% CO 2 , balance N 2 ) applied at different levels of underpressure (ref. ambient). In the first set of experiments (n=19), mucosal perfusion parameters were recorded using a Laser Doppler Flowmeter for 60 min before and 60 min after exposure to the experimental conditions. In the second set of experiments (n=19 chinchillas, 38 ears), the MEs were exposed to the gas mixtures and then maintained for 60 min at ambient pressure or at negative pressures of -200, -400, -600 mmH 2 O. Fifty minutes into the experiment, the animals were injected intravenously with 60 mg/kg of horseradish peroxidase (HRP). The animals were killed and existing effusion was aspirated, its volume recorded and then analyzed for total protein. From surface preparations of the ME mucosa, vascular leakage sites were measured as percent total surface area using an image analysis program with the threshold window set to discriminate HRP stain. Results: Throughout the 120 min in the first set of experiments, the measured MBF parameters decreased in all exposure groups. Comparisons among groups for the absolute magnitude of the change from baseline showed that high local CO 2 partial pressures decreased MBF and ME underpressures increased MBF, but the effects did not achieve statistical significance. The results of the second set of experiments demonstrated no effect of gas composition on any of the measured parameters of vascular permeability. All measures of permeability were linearly related to the magnitude of the underpressure. Conclusion: These data support a role for total ME pressure, but not CO 2 partial pressure in regulating ME MBF and vascular permeability. (C) 2000 Elsevier Science Ireland Ltd.
URI: https://hdl.handle.net/11499/5538
https://doi.org/10.1016/S0385-8146(99)00053-X
ISSN: 0385-8146
Appears in Collections:PubMed İndeksli Yayınlar Koleksiyonu / PubMed Indexed Publications Collection
Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Tıp Fakültesi Koleksiyonu

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