Chloride shift

Chloride shift

Chloride shift (also known as the Hamburger shift or Hamburger's phenomenon, named after Hartog Jakob Hamburger (1859–1924), Dutch physiologist) is a process which occurs in a cardiovascular system and refers to the exchange of bicarbonate (HCO3-) and chloride (Cl-) across the membrane of red blood cells.[1] Carbon dioxide (CO2) generated in tissues enters the blood and dissolves in water in the red blood cells to form carbonic acid (H2CO3), which then dissociates to form bicarbonate (HCO-3) and a hydrogen ion (H+). When carbon dioxide levels fall as the blood passes through the lungs, bicarbonate levels fall in the serum because the equilibrium shifts to replace CO2, and consequently bicarbonate in the red blood cells will move out into the serum. To balance the charges when bicarbonate exits the cell, a chloride anion from the plasma enters the red blood cell. Reverse changes occur in the lungs when carbon dioxide is eliminated from the blood. Here, the exchange of bicarbonate for chloride in red blood cells flushes the bicarbonate from the blood and increases the rate of gas exchange.[2] This chloride shift may also regulate the affinity of hemoglobin for oxygen through the chloride ion acting as an allosteric effector.[3]

Reaction (as it occurs in the lung)

   PLASMA                RBC

   HCO3- --> --> -->    HCO3-
 
   Na+                   K+

   Cl- <-- <-- <-- <--   Cl-

Bicarbonate in the red blood cell (RBC) exchanging with chloride from plasma.

Key feature to remember here is that,carbonic anhydrase enzyme is found inside the red blood cells and not in the plasma. So carbon dioxide that diffuses into the blood from tissue, further diffuses into red blood cell, gets converted to bicarbonate. This bicarbonate moves down its concentration gradient into the plasma. To maintain electroneutrality anion chloride moves from plasma into the red blood cell.

References

  1. ^ Crandall ED, Mathew SJ, Fleischer RS, Winter HI, Bidani A (1981). "Effects of inhibition of RBC HCO3-/Cl- exchange on CO2 excretion and downstream pH disequilibrium in isolated rat lungs". J. Clin. Invest. 68 (4): 853–62. doi:10.1172/JCI110340. PMC 370872. PMID 6793631. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=370872. 
  2. ^ Westen EA, Prange HD (2003). "A reexamination of the mechanisms underlying the arteriovenous chloride shift". Physiol. Biochem. Zool. 76 (5): 603–14. doi:10.1086/380208. PMID 14671708. 
  3. ^ Nigen AM, Manning JM, Alben JO (25 June 1980). "Oxygen-linked binding sites for inorganic anions to hemoglobin". J. Biol. Chem. 255 (12): 5525–9. PMID 7380825. http://www.jbc.org/cgi/reprint/255/12/5525. 



Wikimedia Foundation. 2010.

Игры ⚽ Поможем сделать НИР

Look at other dictionaries:

  • chloride shift — shift n the passage of chloride ions from the blood plasma into the red blood cells when carbon dioxide enters the plasma from the tissues and their return to the plasma when the carbon dioxide is discharged in the lungs that is a major factor… …   Medical dictionary

  • chloride shift — noun : the passage of chloride ions from the plasma into the red blood cells when carbon dioxide enters the plasma from the tissues and their return to the plasma when the carbon dioxide is discharged in the lungs, a major factor both in… …   Useful english dictionary

  • shift — SYN: change. SEE ALSO: deviation. antigenic s. mutation, i.e., sudden change in molecular structure of RNA/DNA in microorganisms, especially viruses, which produces new strains; hosts previously exposed to other strains have little or no acquired …   Medical dictionary

  • Chloride potassium symporter 5 — Solute carrier family 12 (potassium/chloride transporter), member 5 Identifiers Symbols SLC12A5; KCC2; KIAA1176 External IDs …   Wikipedia

  • Ytterbium(III) chloride — Ytterbium(III) chloride …   Wikipedia

  • Titanium(III) chloride — β TiCl3 viewed along the chains …   Wikipedia

  • secondary buffering — chloride shift …   Medical dictionary

  • Life Sciences — ▪ 2009 Introduction Zoology       In 2008 several zoological studies provided new insights into how species life history traits (such as the timing of reproduction or the length of life of adult individuals) are derived in part as responses to… …   Universalium

  • Hemoglobin — Hemoglobin, human, adult (heterotetramer, (αβ)2) Structure of human hemoglobin. The protein s α and β subunits are in red and blue, and the iron containing heme groups in green. Fro …   Wikipedia

  • Oxygen–haemoglobin dissociation curve — The oxygen–haemoglobin dissociation curve (or oxygen–hemoglobin dissociation curve) plots the proportion of haemoglobin in its saturated form on the vertical axis against the prevailing oxygen tension on the horizontal axis. The oxyhaemoglobin… …   Wikipedia

Share the article and excerpts

Direct link
… Do a right-click on the link above
and select “Copy Link”