MECHANISM OF ACUTE HYPOXIC PULMONARY VASOCONSTRICTION

Özge UZUN*°, A.Tuncay DEMIRYÜREK*, Ilker KANZIK*

*Gazi University, Faculty of Pharmacy, Department of Pharmacology, Ankara, TURKEY.
°Corresponding Author

Summary:
Hypoxic pulmonary vasoconstriction (HPV) is a physiological mechanism that optimizes the matching of perfusion to ventilation in the lungs. Despite intensive studies, underlying mechanism of HPV and its difference from sistemic circulation remain unknown. Investigations of HPV mechanism intensify on two hypothesis: HPV, which depends on endothelium, is indirect hypothesis.The direct hypothesis, on the other hand, is that HPV is caused by a direct action on vascular smooth muscle cells. However, studies demonstrate that hypoxia can modify cell metabolism and enzyme activity. Decrease in oxygen pressure also affects the functions of ion channels. Determination of the underlying mechanisms of HPV may provide new approaches for the treatment of pulmonary diseases associated with hypoxic vasoconstriction.

Key words:
Hypoxia, Pulmonary Artery, Pulmonary Vein, Endothelium, Smooth Muscle, Second Messengers.