Euler–Liljestrand mechanism

The Euler–Liljestrand mechanism describes the connection between ventilation and blood circulation (perfusion) of the lung. If the ventilation in a part of the lung decreases, this leads to local hypoxia and to vasoconstriction in that part. This so-called shunt is an adaptive mechanism that is beneficial, because it causes blood to pass the lung without being oxygenated. The mechanism was discovered by two Swedish pharmacologists, Ulf von Euler and Göran Liljestrand at the Department of Pharmacology of Karolinska Institute in Stockholm.

The molecular mechanism seems to be mediated by oxygen-sensitive potassium ion channels in the cell membrane of pulmonary smooth muscle. With a low partial pressure of oxygen, these channels are blocked, leading to the depolarization of the cell membrane. Calcium channels are activated and cause the influx of Ca²⁺ ions over the membrane and to the release of calcium from the endoplasmic reticulum. The rise of calcium concentration causes contraction of the blood vessels smooth muscle fibers and the resulting vasoconstriction. Histamine has also been implicated in this mechanism.

References

• Von Euler, US; Liljestrand, G (1946). "Observations on the pulmonary arterial blood pressure in the cat". Acta Physiol. Scand. 12 (301–320)
• Völkel, N; Duschek, W; Kaukel, E; Beier, W; Siemssen, S; Sill, V (1975). "Histamine-an important mediator for the Euler-Liljestrand mechanism?". Pneumonologie. Pneumonology. 152 (1-3): 113–21. doi:10.1007/BF02101579. PMID 171630. 
• Porcelli, RJ; Viau, A; Demeny, M; Naftchi, NE; Bergofsky, EH (1977). "Relation between hypoxic pulmonary vasoconstriction, its humoral mediators and alpha-beta adrenergic receptors". Chest. 71 (2 suppl): 249–51. PMID 12924. 

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