Mild Hypoxia Impairs Chromatic Sensitivity in the Mesopic Range

2008 ◽  
Vol 49 (2) ◽  
pp. 820 ◽  
Author(s):  
Desmond M. Connolly ◽  
John L. Barbur ◽  
Sarah L. Hosking ◽  
Ian R. Moorhead
Keyword(s):  
Chromatic Sensitivity ◽  
Mild Hypoxia

A nitroreductase-activatable near-infrared theranostic photosensitizer for photodynamic therapy under mild hypoxia

2020 ◽  
Vol 56 (43) ◽  
pp. 5819-5822
Author(s):  
Jing Zheng ◽  
Yongzhuo Liu ◽  
Fengling Song ◽  
Long Jiao ◽  
Yingnan Wu ◽  
...  
Keyword(s):  
Photodynamic Therapy ◽  
Triplet State ◽  
Near Infrared ◽  
Mild Hypoxia

In this study, a near-infrared (NIR) theranostic photosensitizer was developed based on a heptamethine aminocyanine dye with a long-lived triplet state.

Loss of chromatic sensitivity in AMD and diabetes: a comparative study

2010 ◽  
Vol 30 (5) ◽  
pp. 705-716 ◽  
Author(s):  
M. O’Neill-Biba ◽  
S. Sivaprasad ◽  
M. Rodriguez-Carmona ◽  
J. E. Wolf ◽  
J. L. Barbur
Keyword(s):  
Comparative Study ◽  
Chromatic Sensitivity

Participation of Na+ channels in the response of carotid body chemoreceptor cells to hypoxia

1994 ◽  
Vol 267 (3) ◽  
pp. C738-C744 ◽  
Author(s):  
A. Rocher ◽  
A. Obeso ◽  
M. T. Cachero ◽  
B. Herreros ◽  
C. Gonzalez
Keyword(s):  
Carotid Body ◽  
Neurotransmitter Release ◽  
Marked Reduction ◽  
Adult Rabbit ◽  
Na Channels ◽  
Na Current ◽  
Chemoreceptor Cells ◽  
Cell Depolarization ◽  
First Time ◽  
Mild Hypoxia

The role played by Na+ channels of carotid body (CB) chemoreceptor cells was investigated by studying the effects of tetrodotoxin (TTX) on the release of 3H-labeled catecholamines ([3H]CA) by adult rabbit CBs previously incubated with the precursor [3H]tyrosine. TTX inhibited partially the release of [3H]CA elicited by mild hypoxia (10 or 7% O2) or by depolarizing incubation medium containing 20 or 30 mM KCl, but the response to more intense hypoxia (5 or 2% O2) or to higher KCl concentration (40 or 50 mM) was not significantly affected. The release of [3H]CA elicited by acidic stimuli, either 20% CO2 (pH 6.6) or the protonophore dinitrophenol (100 microM), although comparable in magnitude to that elicited by mild hypoxia, was not modified by TTX. These results provide evidence for the first time that Na+ channels of chemoreceptor cells participate in the transduction of hypoxic stimuli into the neurotransmitter release response of these cells and suggest that Na+ current operates as an amplifying device that enhances the initial cell depolarization mediated by the closure of the O2-sensitive K+ channels. Sympathetic denervation of CBs was followed by a marked reduction in the release of [3H]CA elicited by veratridine or by 20 mM KCl, suggesting that the number of Na+ channels in chemoreceptor cells decreases after denervation.

scholarly journals Aerobic and anaerobic metabolism for the zebrafish, Danio rerio, reared under normoxic and hypoxic conditions and exposed to acute hypoxia during development

2010 ◽  
Vol 70 (2) ◽  
pp. 425-434 ◽  
Author(s):  
WR Barrionuevo ◽  
MN Fernandes ◽  
O Rocha
Keyword(s):  
Danio Rerio ◽  
Anaerobic Metabolism ◽  
Developmental Stages ◽  
Acute Hypoxia ◽  
Lactate Concentration ◽  
Growth Delay ◽  
Hypoxic Conditions ◽  
Aerobic And Anaerobic ◽  
Mild Hypoxia

In order to verify the influence of chronic and acute ambient oxygen levels from egg to adult stage of the zebrafish, in vivo oxygen consumption (MO2), critical tensions of oxygen (Pcrit), heart rate (fH) and total body lactate concentration (Lc) were determined for Danio rerio (Hamilton, 1822) raised at 28 °C under normoxic (7.5 mgO2.L-1 or 80 mm.Hg-1) and hypoxic conditions (4.3 mgO2.L-1) and exposed to acute hypoxia during different developmental stages. Our findings confirmed that very early stages do not respond effectively to ambient acute hypoxia. However, after the stage corresponding to the age of 30 days, D. rerio was able to respond to acute hypoxia through effective physiological mechanisms involving aerobic and anaerobic metabolism. Such responses were more efficient for the fishes reared under hypoxia which showed that D. rerio survival capability increased during acclimation to mild hypoxia. Measurements of body mass and length showed that moderate hypoxia did not affect growth significantly until the fish reached the stage of 60 days. Moreover, a growth delay was verified for the hypoxic-reared animals. Also, the D. rerio eggs-to-larvae survival varied from 87.7 to 62.4% in animals reared under normoxia and mild hypoxia, respectively. However, the surviving animals raised under moderated hypoxia showed a better aptitude to regulate aerobic and anaerobic capacities when exposed to acute hypoxia.

Chromatic sensitivity of neurones in area MT of the anaesthetised macaque monkey compared to human motion perception

2005 ◽  
Vol 167 (4) ◽  
pp. 504-525 ◽  
Author(s):  
Igor Riečanský ◽  
Alexander Thiele ◽  
Claudia Distler ◽  
Klaus-Peter Hoffmann
Keyword(s):  
Motion Perception ◽  
Macaque Monkey ◽  
Human Motion ◽  
Area Mt ◽  
Chromatic Sensitivity

Effects of hypoxia and hypercapnia on geniohyoid contractility and endurance

1991 ◽  
Vol 71 (2) ◽  
pp. 709-715 ◽  
Author(s):  
R. J. Salmone ◽  
E. Van Lunteren
Keyword(s):  
Force Production ◽  
Upper Airway ◽  
Muscle Performance ◽  
Severe Hypoxia ◽  
Force Frequency ◽  
Force Output ◽  
Frequency Curve ◽  
Dilator Muscle ◽  
Index Ratio ◽  
Mild Hypoxia

Sleep apnea and other respiratory diseases produce hypoxemia and hypercapnia, factors that adversely affect skeletal muscle performance. To examine the effects of these chemical alterations on force production by an upper airway dilator muscle, the contractile and endurance characteristics of the geniohyoid muscle were examined in situ during severe hypoxia (arterial PO2 less than 40 Torr), mild hypoxia (PO2 45–65 Torr), and hypercapnia (PCO2 55–80 Torr) and compared with hyperoxic-normocapnic conditions in anesthetized cats. Muscles were studied at optimal length, and contractile force was assessed in response to supramaximal electrical stimulation of the hypoglossal nerve (n = 7 cats) or geniohyoid muscle (n = 2 cats). There were no significant changes in the twitch kinetics or force-frequency curve of the geniohyoid muscle during hypoxia or hypercapnia. However, the endurance of the geniohyoid, as reflected in the fatigue index (ratio of force at 2 min to initial force in response to 40-Hz stimulation at a duty cycle 0.33), was significantly reduced by severe hypoxia but not by hypercapnia or mild hypoxia. In addition, the downward shift in the force-frequency curve after the repetitive stimulation protocol was greater during hypoxia than hyperoxia, especially at higher frequencies. In conclusion, the ability of the geniohyoid muscle to maintain force output during high levels of activation is adversely affected by severe hypoxia but not mild hypoxia or hypercapnia. However, none of these chemical perturbations affected muscle contractility acutely.

scholarly journals Chromatic sensitivity of surround suppression in macaque V1 and V2

2010 ◽  
Vol 3 (9) ◽  
pp. 140-140 ◽  
Author(s):  
S. G Solomon ◽  
J. W Peirce ◽  
J. Krauskopf ◽  
P. Lennie
Keyword(s):  
Surround Suppression ◽  
Chromatic Sensitivity

scholarly journals Effects of Normoxia, Hyperoxia, and Mild Hypoxia on Macro-Hemodynamics and the Skeletal Muscle Microcirculation in Anesthetised Rats

2021 ◽  
Vol 8 ◽  
Author(s):  
Elisa Damiani ◽  
Erika Casarotta ◽  
Fiorenza Orlando ◽  
Andrea Carsetti ◽  
Claudia Scorcella ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Negative Impact ◽  
Resistance Index ◽  
Stroke Volume Index ◽  
Microvascular Density ◽  
Vessel Density ◽  
Volume Index ◽  
Flow Index ◽  
Flow Quality ◽  
Mild Hypoxia

Objectives: Excessive oxygen (O2) administration may have a negative impact on tissue perfusion by inducing vasoconstriction and oxidative stress. We aimed to evaluate the effects of different inhaled oxygen fractions (FiO2) on macro-hemodynamics and microvascular perfusion in a rat model.Methods: Isoflurane-anesthetised spontaneously breathing male Wistar rats were equipped with arterial (carotid artery) and venous (jugular vein) catheters and tracheotomy, and randomized into three groups: normoxia (FiO2 21%, n = 6), hyperoxia (FiO2 100%, n = 6) and mild hypoxia (FiO2 15%, n = 6). Euvolemia was maintained by infusing Lactate Ringer solution at 10 ml/kg/h. At hourly intervals for 4 h we collected measurements of: mean arterial pressure (MAP); stroke volume index (SVI), heart rate (HR), respiratory rate (by means of echocardiography); arterial and venous blood gases; microvascular density, and flow quality (by means of sidestream dark field videomicroscopy on the hindlimb skeletal muscle).Results: MAP and systemic vascular resistance index increased with hyperoxia and decreased with mild hypoxia (p < 0.001 in both cases, two-way analysis of variance). Hyperoxia induced a reduction in SVI, while this was increased in mild hypoxia (p = 0.002). The HR increased under hyperoxia (p < 0.05 vs. normoxia at 3 h). Cardiax index, as well as systemic O2 delivery, did not significantly vary in the three groups (p = 0.546 and p = 0.691, respectively). At 4 h, microvascular vessel surface (i.e., the percentage of tissue surface occupied by vessels) decreased by 29 ± 4% in the hyperoxia group and increased by 19 ± 7 % in mild hypoxia group (p < 0.001). Total vessel density and perfused vessel density showed similar tendencies (p = 0.003 and p = 0.005, respectively). Parameters of flow quality (microvascular flow index, percentage of perfused vessels, and flow heterogeneity index) remained stable and similar in the three groups.Conclusions: Hyperoxia induces vasoconstriction and reduction in skeletal muscle microvascular density, while mild hypoxia has an opposite effect.

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