21 dis pigeon blood altitude[1]

8/3/2019 21 Dis Pigeon Blood Altitude[1]

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Effects of ChronicEffects of Chronic

Hypobaric Hypoxia onHypobaric Hypoxia onBlood Oxygen Binding inBlood Oxygen Binding in

PigeonsPigeons

By: Maginniss, Bernstein,By: Maginniss, Bernstein,

Deitch, and PinshowDeitch, and Pinshow


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What is Hypobaric HypoxiaWhat is Hypobaric Hypoxia

HypobaricHypobaric-- below normal pressurebelow normal pressure

HypoxiaHypoxia-- deficiency in the amount ofdeficiency in the amount ofoxygen reaching body tissuesoxygen reaching body tissues


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Tolerance to Chronic HypobaricTolerance to Chronic Hypobaric

Hypoxia:Hypoxia:

Found in many pigeonsFound in many pigeons-- up to 9 kmup to 9 km

WarblersWarblers-- in transoceanic migrationsin transoceanic migrationswith 70 torr pressure and 0with 70 torr pressure and 0C temps.C temps.


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Tolerance Attributed toTolerance Attributed to

Adaptations:Adaptations:

CardiovascularCardiovascular

PulmonaryPulmonary AcidAcid--basebase

MetabolicMetabolic

ThermoregulatoryThermoregulatory


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Central Hypothesis:Central Hypothesis:

Chronic hypoxia leads to changes inChronic hypoxia leads to changes in

HbHb-- OO22 binding and circulating Hbbinding and circulating Hbconcentration.concentration.

These changes increaseThese changes increaseparabronchial Oparabronchial O22 loading andloading andunloading at peripheral tissuesunloading at peripheral tissues


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Problems:Problems:

Pigeons acclimated at 4km showedPigeons acclimated at 4km showed

no changes in blood Pno changes in blood P5050..

Chronic hypoxia led to a right shift inChronic hypoxia led to a right shift in

the Othe O22 equilibrium curve (Oequilibrium curve (O22 EC) inEC) inPekin ducks.Pekin ducks.


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Possible Reasons we seePossible Reasons we see

tolerance:tolerance: Decreased body temp in hypobaricDecreased body temp in hypobaric

birds could increase blood Obirds could increase blood O22 affinity.affinity.

Alkalosis often associated withAlkalosis often associated withaltitude acclimation also oftenaltitude acclimation also oftenincreases Hbincreases Hb-- OO22 affinity, andaffinity, andincrease loading at the lung.increase loading at the lung.

The shape of the OThe shape of the O22 EC, and COEC, and CO22effects can influence Oeffects can influence O22 transporttransport


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Authors Measured:Authors Measured:

HbHb-- OO22 affinityaffinity

OO22 EC shapeEC shape

COCO22 Bohr EffectBohr Effect HbHb-- OO22 temperature coefficienttemperature coefficient

OO22 carrying capacitycarrying capacity

In domestic PigeonsIn domestic Pigeons


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Methods:Methods:

eaSea--level birds maintained at 758level birds maintained at 758

torr, 25torr, 25C, w/ 12L/12D for 5C, w/ 12L/12D for 5--66weeks.weeks.

High

High-- altitude birds were kept at 308altitude birds were kept at 308torr, 25torr, 25C, and 12L/12D for 6 weeks.C, and 12L/12D for 6 weeks.


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Primary Objective:Primary Objective:

To collect data and calculate the OTo collect data and calculate the O22

binding characteristics at altitudebinding characteristics at altitudeunder in vivo conditions.under in vivo conditions.


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Blood OBlood O22 Binding Properties:Binding Properties:

No statisticalNo statisticaldifference betweendifference betweenaltitude and nonaltitude and non--altitude acclimatedaltitude acclimatedbirdsbirds

Reduction of bloodReduction of bloodtemp caused left shifttemp caused left shiftin both groups (top)in both groups (top)


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COCO22 Bohr EffectBohr Effect

Acclimation to highAcclimation to highaltitude did notaltitude did notaffect COaffect CO22 BohrBohr

effect at any tempeffect at any temp

The COThe CO22 BohrBohrcoefficients werecoefficients were

saturationsaturation--independent forindependent forboth groupsboth groups


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OO22 Equilibrium CurvesEquilibrium Curves

Both groups showedBoth groups showedsimilar Osimilar O22 EC shapesEC shapes

w/ no statisticallyw/ no statisticallysignificant difference.significant difference.

At saturation of .5At saturation of .5--.9.9the slope wasthe slope wassignificantly greatersignificantly greaterfor both groups atfor both groups atboth temperatures.both temperatures.


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A Reminder:A Reminder:


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Why we see nonWhy we see non--linear Olinear O22 ECEC

Increased cooperativity is found atIncreased cooperativity is found athigher saturations due tohigher saturations due topolymerization or aggregation of thepolymerization or aggregation of theHb tetramersHb tetramers

As one Hb tetramer is oxygenatedAs one Hb tetramer is oxygenatedthe others become increasinglythe others become increasinglyeasier to oxygenate.easier to oxygenate.


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More Reasons we see nonMore Reasons we see non--linearlinear

OO22 EC:EC:

Allosteric Modifiers (Organic Phosphates)Allosteric Modifiers (Organic Phosphates)regulate Hb function:regulate Hb function:

2,32,3--diphosphoglycerate (DPG)diphosphoglycerate (DPG)

Inositol pentaphosphate (IPP)Inositol pentaphosphate (IPP)--primary in birdsprimary in birds

Asymmetry of curve greatest when IPPAsymmetry of curve greatest when IPPwas closest to 1:1 ratio w/ Hb.was closest to 1:1 ratio w/ Hb.

This acts to increase cooperativity atThis acts to increase cooperativity atsaturation above Psaturation above P5050, increase O, increase O22 uptakeuptakeat the lung and delivery to the tissues.at the lung and delivery to the tissues.


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Blood Composition:Blood Composition:

Acclimatization to high altitude did notAcclimatization to high altitude did notaffect isohemoglobin compositionaffect isohemoglobin composition

compared with the sea level group.compared with the sea level group.


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Chronic Hypobaric HypoxiaChronic Hypobaric Hypoxia

Resulted in Increased:Resulted in Increased: HematocritHematocrit

Hemoglobin concentrationHemoglobin concentration

OO22 capacitycapacity


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Comparisons with other Studies:Comparisons with other Studies:

In sea level pigeon, PIn sea level pigeon, P5050 values arevalues arewithin other published ranges, aswithin other published ranges, aswas the effect of COwas the effect of CO22 on Hbon Hb--OO22coefficients.coefficients.

The COThe CO22 Bohr effect was independentBohr effect was independentof both temperature from 41of both temperature from 41--3737C,C,and Oand O22 saturation levels.saturation levels.


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Blood OBlood O22 Transport:Transport:

HbHb--OO22 binding properties similar inbinding properties similar inboth groups.both groups.

No significant differences in:No significant differences in: Blood OBlood O22 affinityaffinity

COCO22 Bohr EffectBohr Effect OO22 EC shapeEC shape

HbHb--OO22 temp coefficienttemp coefficient


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Altitude Blood Adaptations:Altitude Blood Adaptations:

Increased HbIncreased Hb--OO22affinity associatedaffinity associated

with hypoxiawith hypoxia--inducedinducedhypothermiahypothermia

Increased OIncreased O22 carryingcarryingcapacitycapacity


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Altitude Acclimatized Pigeons:Altitude Acclimatized Pigeons:

In vivo demonstrate ionicIn vivo demonstrate ioniccompensation for the respiratorycompensation for the respiratoryalkalosis.alkalosis.

Likely via a metabolic alteration ofLikely via a metabolic alteration ofblood acidblood acid--base state and renalbase state and renalcompensation.compensation.

This results in the acclimated birdThis results in the acclimated birdnot relying on hyperventilation tonot relying on hyperventilation toincrease Oincrease O22 affinity.affinity.


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Arterial Oxygen Content:Arterial Oxygen Content:

Control birds at 30 torr oxygenControl birds at 30 torr oxygencontent was only 7.6 vol%content was only 7.6 vol%

While altitude acclimated birds at 30While altitude acclimated birds at 30torr content was 14.2 vol%torr content was 14.2 vol%

87% increase over controls87% increase over controls Controls would need to fly at 49 Torr toControls would need to fly at 49 Torr to

gain equal Ogain equal O22 content.content.


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Not justNot just [[HbHb]] increaseincrease

The increase in the Hb concentrationThe increase in the Hb concentrationonly brings us to 10.8 vol%only brings us to 10.8 vol%

Therefore, the increased Hb affinityTherefore, the increased Hb affinitydue to hypothermia along with thedue to hypothermia along with theincrease in Hb concentration allowsincrease in Hb concentration allows

the large Othe large O22 carrying capacity, and acarrying capacity, and agreater gradient to facilitategreater gradient to facilitateunloading at the tissues.unloading at the tissues.


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Hypothermia Theories:Hypothermia Theories:

Inhalation of very cold air (Inhalation of very cold air (--2323C)C)should increase respiratory Oshould increase respiratory O22loading.loading.

Alternatively the flight musclesAlternatively the flight musclesmaintain a much higher temp andmaintain a much higher temp andtherefore should increase Otherefore should increase O22unloading at these sites.unloading at these sites.


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Thank you!Thank you!

21 dis pigeon blood altitude[1]

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