biochem doubt

[missiondds]

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DOES PYRUVATE KINASE DEFICIENCY CAUSE INCREASE IN LACTATE OR DECREASE IN LACTATE?


I saw 2 question in which one mentioned PKdefieciency caused reduction in lactate, while the other mentioned it increased levels of lactate.

As lactate dehydrogenase enzyme levels are normal in pk def... more pyruvate would be converted to lactate (in rbcs). but as PK is the enzyme which catalyzes the conversion of PEP____>pyruvate... i doubt how lactate levels would rise?

pls help.

 

[Sinatra Frank]

DOES PYRUVATE KINASE DEFICIENCY CAUSE INCREASE IN LACTATE OR DECREASE IN LACTATE?


I saw 2 question in which one mentioned PKdefieciency caused reduction in lactate, while the other mentioned it increased levels of lactate.

As lactate dehydrogenase enzyme levels are normal in pk def... more pyruvate would be converted to lactate (in rbcs). but as PK is the enzyme which catalyzes the conversion of PEP____>pyruvate... i doubt how lactate levels would rise?


pls help.

i will try to help..
pk as u said turn pep to purauvte as part of glycolysis.
LDH is enz that turns pyravate to lactate...

so if u have deffeicency in PK..u wont have puruvate-->no substrate to LDH to make lactic acid.
hence the levels of lactic acid will decreace.

in addition pk defecincy cause hemolytic anemia..
the anaerobic glycolysis is impaired and this affects the membrane of rbc-->hemplytic anemia. this shows u that lactate are low.. the anemia is due to inability to produce nad+-->no atp that is needed to maintain membrane form of rbc.

 

[missiondds]

i will try to help..
pk as u said turn pep to purauvte as part of glycolysis.
LDH is enz that turns pyravate to lactate...

so if u have deffeicency in PK..u wont have puruvate-->no substrate to LDH to make lactic acid.
hence the levels of lactic acid will decreace.

in addition pk defecincy cause hemolytic anemia..
the anaerobic glycolysis is impaired and this affects the membrane of rbc-->hemplytic anemia. this shows u that lactate are low.. the anemia is due to inability to produce nad+-->no atp that is needed to maintain membrane form of rbc.

but as all hemolytic anemias cause an increase in ldh which would cause lactate to increase.. coz nad levels are depleted n nadh levels are high.. the deciding factor on which ldh works PYRUVAT TO LACATE (REVERSABLE RXN)

 

[Sinatra Frank]

but as all hemolytic anemias cause an increase in ldh which would cause lactate to increase.. coz nad levels are depleted n nadh levels are high.. the deciding factor on which ldh works PYRUVAT TO LACATE (REVERSABLE RXN)

man u r complicating things..think simpel.🙂
no puruvate means no substarte to LDH! so no lactate! and i dont know from where is the assumption that all hemplytic anemias cause increase in lactic acid.

this is a quote from emedecine website :

In patients with pyruvate kinase (PK) deficiency, a metabolic block is created in the pathway at the level of the deficient enzyme. Intermediate byproducts and various glycolytic metabolites proximal to the metabolic block accumulate in the RBCs, while such cells become depleted of the distal products in the pathway, such as lactate and ATP.

hope this will make u convinced 🙂
good luck and please post more questions.. this is a great way to learn and refesh topics.. 🙂 best of luck

 

[missiondds]

man u r complicating things..think simpel.🙂
no puruvate means no substarte to LDH! so no lactate! and i dont know from where is the assumption that all hemplytic anemias cause increase in lactic acid.

this is a quote from emedecine website :

In patients with pyruvate kinase (PK) deficiency, a metabolic block is created in the pathway at the level of the deficient enzyme. Intermediate byproducts and various glycolytic metabolites proximal to the metabolic block accumulate in the RBCs, while such cells become depleted of the distal products in the pathway, such as lactate and ATP.

hope this will make u convinced 🙂
good luck and please post more questions.. this is a great way to learn and refesh topics.. 🙂 best of luck

so IN THAT CASEPEP SHOULD ACCUMALATE SINCE NO SUBSTRATE FOR pk FOR ITS ACTIVITIY... SO PLS ANSWER THIS QUESTION FOR ME.

A PT. 18 MONTHS OLD REPORTS WITH HEMOLYTIC ANEMIA/JAUNDICE/. BLOOD SMEAR INDICATES RBC ARE RIGID IN APPEARANCE.A PK DEF. IS DIAGNOSED. SINCE PYRUVATE IS THE LAST SATEP OF THE PATHWAY WHAT WILL BUILD UP. WHAT PRODUCT IN PATHWAY WILL BE MADE IN ABNORMAL AMOUNTS?

ACETYL COA
GLUCOSE
LACTATE
OXALOACETATE
GLYCOGEN.

I DONT MEAN TO COMPLICATE STUFF I HAVE WASTED ENUF TIME TRYING TO FIND A SOLUTION!!!

FYI ANSWER IS LACTATE!!
EXPLATIONATION:SINCE RBCS HAVE NO MITOCHONDRIA... SO NO ACTEYL COA/GLUCOSE./OXALOACETE.ONLY ENZYME IN RBCS IS LDH. DEPENDING UPON THE LEVELS OF PYRUVATE PRESENET(EVEN MINISCULE) FOR EACH RBC.. LACATE IS PRODUCED.

 

[missiondds]

q2 A PTWITH SYMPTOMS OF WEAKNESS/SHORTNESS OF BREATH/HB LEVELS ARE 5/7 RBCS SHOW ABNORMALLY LOW LEVELS OF LACTATE PRODUCTION. A DEFICIENCY OF WHICH ENZYMES WOULD BE MOST LIKELY COZ OF THE PTS ANEMIA?

pg isomarase
pfk
pk
hexokinase
ldh.

any guess s.frank??

 

[njsmahal]

so IN THAT CASEPEP SHOULD ACCUMALATE SINCE NO SUBSTRATE FOR pk FOR ITS ACTIVITIY... SO PLS ANSWER THIS QUESTION FOR ME.

A PT. 18 MONTHS OLD REPORTS WITH HEMOLYTIC ANEMIA/JAUNDICE/. BLOOD SMEAR INDICATES RBC ARE RIGID IN APPEARANCE.A PK DEF. IS DIAGNOSED. SINCE PYRUVATE IS THE LAST SATEP OF THE PATHWAY WHAT WILL BUILD UP. WHAT PRODUCT IN PATHWAY WILL BE MADE IN ABNORMAL AMOUNTS?

ACETYL COA
GLUCOSE
LACTATE
OXALOACETATE
GLYCOGEN.

I DONT MEAN TO COMPLICATE STUFF I HAVE WASTED ENUF TIME TRYING TO FIND A SOLUTION!!!

FYI ANSWER IS LACTATE!!
EXPLATIONATION:SINCE RBCS HAVE NO MITOCHONDRIA... SO NO ACTEYL COA/GLUCOSE./OXALOACETE.ONLY ENZYME IN RBCS IS LDH. DEPENDING UPON THE LEVELS OF PYRUVATE PRESENET(EVEN MINISCULE) FOR EACH RBC.. LACATE IS PRODUCED.

dude i just checked lippincot and it says the reason for lactic acidosis in the hemolytic anemias is as PK deficiency is there so there wont be any source of energy for the RBC as you read in the explaination so ther ewould be hemolysis. NOW DUE TO HEMOLYSIS THERE WOULD BE DECREASED AMOUNT FO OXYGEN TO TEH PERIPHERAL TISSUES AND HENCE THE PYRUVATE IS DIVERTED TO ANAEROBIC PROCESS AND HENCE LACTIC ACID IS PRODUCED SO THERE WOULD BE AN INCREASE IN THE LEVELS OF LACTIC ACID IN THE BLOOD.

i guess thats the key

 

[missiondds]

I agree lactate level will be increased mainly due to elevated nadh level leading to anerobic respiration..

the key to question 2 is PK deficiency.

 

[Sinatra Frank]

dude i just checked lippincot and it says the reason for lactic acidosis in the hemolytic anemias is as PK deficiency is there so there wont be any source of energy for the RBC as you read in the explaination so ther ewould be hemolysis. NOW DUE TO HEMOLYSIS THERE WOULD BE DECREASED AMOUNT FO OXYGEN TO TEH PERIPHERAL TISSUES AND HENCE THE PYRUVATE IS DIVERTED TO ANAEROBIC PROCESS AND HENCE LACTIC ACID IS PRODUCED SO THERE WOULD BE AN INCREASE IN THE LEVELS OF LACTIC ACID IN THE BLOOD.

i guess thats the key

hey there🙂

i think u r wrong.. and ill explain why..

pk def will casue hemolytic anemia-agree
pk def will casue hypoxia- agree
pk def will casue acidosis-agree

but how will cell will switch to anaerobic glycolysis if pk is defect?
the glycolyisis is stuck!
i know that lactic acidosis will occur on PDH deficency not in PK def.

i know that in pk def..u cant proceed so u go backwords-->this is why 2.3 BPG will increase..

im looking forword to ur answer.. how lactic acodisis can occur in the periphary if all cells are affected from pk def?

 

[njsmahal]

hey there🙂

i think u r wrong.. and ill explain why..

pk def will casue hemolytic anemia-agree
pk def will casue hypoxia- agree
pk def will casue acidosis-agree

but how will cell will switch to anaerobic glycolysis if pk is defect?
the glycolyisis is stuck!
i know that lactic acidosis will occur on PDH deficency not in PK def.

i know that in pk def..u cant proceed so u go backwords-->this is why 2.3 BPG will increase..

im looking forword to ur answer.. how lactic acodisis can occur in the periphary if all cells are affected from pk def?

http://books.google.com/books?id=Pm...&hl=en&sa=X&oi=book_result&resnum=2&ct=result
just lemme know what it means.. maybe i am wrong and you ahve a point there about the whole thing. coz if its deficient in rbc its deficient everywhere

 

[Sinatra Frank]

http://books.google.com/books?id=Pm...&hl=en&sa=X&oi=book_result&resnum=2&ct=result
just lemme know what it means.. maybe i am wrong and you ahve a point there about the whole thing. coz if its deficient in rbc its deficient everywhere

hey.. problem is solved.. and i was wrong damn it! im gonna score below 90..

the thing is that pk def is RESTRICTED TO RBC
so the periphery will switch to anaerobic due to hypoxia..
but hey at least my answers was right regarding what is happening INSIDE the rbc.. 🙂

 

[Sinatra Frank]

q2 A PTWITH SYMPTOMS OF WEAKNESS/SHORTNESS OF BREATH/HB LEVELS ARE 5/7 RBCS SHOW ABNORMALLY LOW LEVELS OF LACTATE PRODUCTION. A DEFICIENCY OF WHICH ENZYMES WOULD BE MOST LIKELY COZ OF THE PTS ANEMIA?

pg isomarase
pfk
pk
hexokinase
ldh.

any guess s.frank??

well here i was right the question says :RBCS SHOW ABNORMALLY LOW LEVELS OF LACTATE PRODUCTION---> pk def 🙂

 

[njsmahal]

hey.. problem is solved.. and i was wrong damn it! im gonna score below 90..

the thing is that pk def is RESTRICTED TO RBC
so the periphery will switch to anaerobic due to hypoxia..
but hey at least my answers was right regarding what is happening INSIDE the rbc.. 🙂

thats exactly what i found... just a little later.... lol. hahaha dude... you are scaring me.. whenever i think i am right you come up with a different answer and on top of that you are saying that??? lol say you will score below 95 if you wan tso taht i have a window to work on

 

[Sinatra Frank]

thats exactly what i found... just a little later.... lol. hahaha dude... you are scaring me.. whenever i think i am right you come up with a different answer and on top of that you are saying that??? lol say you will score below 95 if you wan tso taht i have a window to work on

lol.. first of all in every debate u won.. so u have nothing to worry about..
i am confident that u will get a comepetative score..
im on the other hand getting by *ss kicked in Kaplan q bank..my moral is sooo low 🙁
btw.. i was aiming above 90 not 95 😀
but it doesnt matter in last kaplan q in pathology (did 20 questions i got 70% )