This chapter is most relevant to Section F8(ii) from the 2017 CICM major Syllabus, i beg your pardon expects the exam candidates to be able to "describe the carbon dioxide carriage in blood including ...the chloride shift".

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In summary: 


The chloride transition or "Hamburger effect" explains the activity of chloride right into RBCs i beg your pardon occurs as soon as the buffer impacts of deoxygenated haemoglobin increase the intracellular bicarbonate concentration, and also the bicarbonate is exported indigenous the RBC in exchange because that chloride.This outcomes in a distinction of 2-4 mmol/L of chloride between the arterial and also venous blood (and a similar difference in bicarbonate concentration).The system of the chloride shift:Chloride moves into erythrocytes, and also bicarbonate move out, in venous blood.CO2 diffuses into the red cellsThere, the is converted to bicarbonate by carbonic anhydraseBicarbonate is climate pumped the end of the red cell, and also chloride pumped into it, through the tape 3 exchange protain. This whole procedure happens really rapidly, well within the turn around timeThe reverse occasions take location in the pulmonary capillaries:Bicarbonate is pumped earlier into the red cell, and also chloride pumped outCarbonic anhydrase converts bicarbonate ago into carbon dioxide and waterThe chloride change has signficant impacts for the organism:It mitigates the adjust in pH which would certainly otherwise happen in the peripheral circulation as result of metabolic byproducts (mainly CO2)It rises the CO2-carrying capacity of the venous bloodIt increases the unloading of oxgyen, since of the allosteric modulation the the haemoglobin tetramer by chloride (it stabilises the deoxygenated T-state)

Westen & Prange (2003) give a reasonable overview of the situation, but their article is paywalled. So is the excellent record by Klocke (1988) which basically goes through all the procedures in the chloride shift process in wonderful detail. Surely if you room going to be throwing money roughly you may also buy the official exam textbook. Unfortunately, Hartog Jacob Hamburger"s original file on "Anionenwanderungen in Serum und Blut" is no available, yet perhaps that is because that our own good.

Definition of the chloride shift:

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

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

There is most likely something more official out there, but most authors offer a description which is so close to the one above that it would certainly be meaningless come repeat lock all. In short, if this ever before comes increase in a viva of part sort, so long as one provides the words "chloride" and also "erythrocytes" in the very same sentence, one should be near to fifty percent marks already. The most important points are:

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

Mechanism the the chloride shift

The molecular mechanisms for the chloride shift are defined in detail below. In summary, this phenomenon is only feasible because the the visibility of carbonic anhydrase in RBCs. That is seen as a critically important facet (as that is focused there, yet essentially missing from the bloodstream otherwise). There is no it, the reaction converting CO2 to HCO3- would it is in painfully slow. Through massive quantities of erythcyte carbonic anhydrase, we have the right to instead counting on this molecular transactions come be finish in the an are of one circulatory time. In fact, because all the required proteins are available in enormous concentrations, the reaction is incredibly fast. Wieth & Brahm (1980) had figured out that 99% that the chloride shift process is complete within about 700 milliseconds.

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

Magnitude that the chloride shift

With all this talk of shifting, how much chloride actually shifts? This impact is not precisely seismic. For instance, after determining what electrolyte movements should occur making use of quantitative physicochemical analysis, western & Prange (2003) drained blood from healthy and balanced volunteers and also subjected it to "venous-ification" by exposure come a hypoxic and also hypercapnic atmosphere. In ~ a simulated venous gas concentration, the typical chloride change of the samples was roughly 2.4 mmol/L. Through a greater haematocrit, closer come 0.55 (they cheated by centrifuge yet there really are world out there through such haematocrit values) the investigators were able to measure up a chloride change of about 4.3 mmol/L. 

Significance of the chloride shift:

Why is this phenomenon important? Well:

Mitigation of pH adjust in the peripheral circulation: pH that 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 transferring capacity that the blood:  the impact of shuttling chloride into the red cells and bicarbonate the end of them increases the total potential bicarbonate carriage by the venous blood, i m sorry is an excellent because many CO2 is carried as bicarbonate.

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

Klocke, Robert A. "Velocity the CO2 exchange in blood."Annual testimonial 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 major polypeptides of the person erythrocyte membrane."Biochemistry10.13 (1971): 2606-2617.

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

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