Myoglobin Buffer?

[Thoroughbred_Med]

A question from TBR:

"Which of the following is least likely to act as a buffer during the formation of urine in the nephron?

A) inorganic phosphate
B) bicarbonate
C) Myoglobin
D) hemoglobin"


The answer is D. hemoglobin. I understand A and B, but do not know anything about myoglobin acting as a buffer. Can anyone help? thanks!

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[jul059]

A question from TBR:

"Which of the following is least likely to act as a buffer during the formation of urine in the nephron?

A) inorganic phosphate
B) bicarbonate
C) Myoglobin
D) hemoglobin"


The answer is D. hemoglobin. I understand A and B, but do not know anything about myoglobin acting as a buffer. Can anyone help? thanks!

I am also puzzled by this question. Anyone can enlighten us?

 

[Doogie.Howser]

You have to think about what's actually freely roaming in the blood stream. Hemoglobin is housed by the RBC, while myoglobin will be roaming freely if there is tissue breakdown that releases myoglobin into the blood stream in times of stress. Now, hemoglobin CAN be free roaming in the blood stream if the RBC is lysed. If all factors occur and we imagine that hemoglobin and myoglobin are free roaming in the blood stream, which protein will most likely be seen in urine? Myoglobin as you know is smaller and therefore will be more likely found in the urine. In fact, myoglobin is often found in the urine. Hope this helps!

 

[Nugester]

As Doogie stated, when you have rhabdomyolysis you break down muscle and this can be detected in urine. This implies there is probably some kind of buffering capability.