This thing is most relevant to Section F8(ii) from the 2017 CICM major Syllabus, i m sorry expects the exam candidates to it is in able to "describe the carbon dioxide carriage in blood including ...the chloride shift".

You are watching: What is the chloride shift?

 

In summary: 


The chloride transition or "Hamburger effect" explains the activity of chloride into RBCs which occurs as soon as the buffer impacts of deoxygenated haemoglobin increase the intracellular bicarbonate concentration, and the bicarbonate is exported from the RBC in exchange because that chloride.This results in a difference of 2-4 mmol/L of chloride in between the arterial and also venous blood (and a comparable difference in bicarbonate concentration).The mechanism of the chloride shift:Chloride moves right into erythrocytes, and also bicarbonate move out, in venous blood.CO2 diffuses right into the red cellsThere, that is converted to bicarbonate through carbonic anhydraseBicarbonate is then pumped out of the red cell, and chloride pumped right into it, by the tape 3 exchange protain. This whole process happens an extremely rapidly, well within the circulating timeThe reverse occasions take place in the pulmonary capillaries:Bicarbonate is pumped back into the red cell, and chloride pumped outCarbonic anhydrase counter bicarbonate earlier into carbon dioxide and waterThe chloride change has signficant effects for the organism:It mitigates the change in pH which would otherwise occur in the peripheral circulation due to metabolic byproducts (mainly CO2)It rises the CO2-carrying volume of the venous bloodIt boosts the unloading the oxgyen, due to the fact that of the allosteric modulation that the haemoglobin tetramer through chloride (it stabilises the deoxygenated T-state)

Westen & Prange (2003) give a reasonable summary of the situation, yet their short article is paywalled. So is the excellent file by Klocke (1988) which usually goes through all the steps in the chloride shift process in wonderful detail. Surely if you are going to be throwing money around you may too buy the main exam textbook. Unfortunately, Hartog Jacob Hamburger"s original file on "Anionenwanderungen in Serum und Blut" is no available, however perhaps the is for our very own good.

Definition the the chloride shift:

Westen & Prange (2003) define the chloride change as:

"the activity of chloride ion from the plasma into red blood cells as blood undergoes the shift from arterial come venous gas partial pressures" 

There is probably something an ext official out there, however most authors give a summary which is for this reason close to the one above that it would certainly be meaningless to repeat castle all. In short, if this ever before comes up in a viva of part sort, so long as one supplies the words "chloride" and also "erythrocytes" in the exact same sentence, one must be near to fifty percent marks already. The most important points are:

Chloride moves right into erythrocytes, and also bicarbonate moves out, in venous blood.The reverse occasions take ar in the pulmonary capillaries

Mechanism the the chloride shift

The molecular mechanisms for the chloride change are explained in detail below. In summary, this phenomenon is only possible because the the visibility of carbonic anhydrase in RBCs. The is viewed as a critically important aspect (as that is concentrated there, yet essentially absent from the bloodstream otherwise). Without it, the reaction converting CO2 come HCO3- would be painfully slow. V massive amounts of erythcyte carbonic anhydrase, we can instead count on these molecular transactions to be finish in the an are of one circulatory time. In fact, due to the fact that all the required proteins are accessible in substantial concentrations, the reaction is very fast. Wieth & Brahm (1980) had figured out that 99% of the chloride shift process is complete within around 700 milliseconds.

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Yes, those potato-looking things are erythrocytes. The numbers came from west & Prange (2003), whose experiments are discussed below.

Magnitude that the chloride shift

With all this speak of shifting, just how much chloride in reality shifts? This impact is not precisely seismic. Because that instance, after identify what electrolyte movements should occur using quantitative physicochemical analysis, west & Prange (2003) drained blood from healthy and balanced volunteers and also subjected it to "venous-ification" through exposure come a hypoxic and also hypercapnic atmosphere. In ~ a simulated venous gas concentration, the typical chloride shift of the samples was around 2.4 mmol/L. With a greater haematocrit, closer to 0.55 (they cheated through centrifuge however there really are world out there v such haematocrit values) the investigators were able to measure up a chloride transition of about 4.3 mmol/L. 

Significance the the chloride shift:

Why is this phenomenon important? Well:

Mitigation the pH adjust in the peripheral circulation: pH the the peripheral blood would readjust significantly more if deoxygenated RBCs were no there to buffer the acid and also sequester the chloride.Increase in the CO2 moving capacity the the blood:  the result of shuttling chloride into the red cells and also bicarbonate out of them boosts the full potential bicarbonate carriage by the venous blood, which is an excellent because most CO2 is lugged as bicarbonate.

Westen, Edward A., and also Henry D. Prange. "A reexamination that the mechanisms underlying the arteriovenous chloride shift."Physiological and Biochemical Zoology76.5 (2003): 603-614.

Klocke, Robert A. "Velocity the CO2 exchange in blood."Annual review of physiology50.1 (1988): 625-637.

Hamburger, H. J. "Anionenwanderungen in Serum und Blut unter dem Einfluss von CO2, Säure und Alkali."Biochem Z86 (1918): 309-324.

Fairbanks, G., Theodore L. Steck, and D. F. H. Wallach. "Electrophoretic analysis of the significant polypeptides that the human being erythrocyte membrane."Biochemistry10.13 (1971): 2606-2617.

Wieth, J. O., and also J. Brahm. "Kinetics of bicarbonate exchange in human red cells—physiological implications."Membrane deliver in erythrocytes. Munksgaard, Copenhagen(1980): 467-487.

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Brix, Ole, et al. "The chloride shift may facilitate oxygen loading and unloading to/from the hemoglobin native the brown bear (Ursus arctos L.)."Comparative biochemistry and physiology. B, compare biochemistry95.4 (1990): 865-868.