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VI.4. The role of the endothelium-derived hyperpolarizing factor (EDHF)

The smooth muscle cells are hyperpolarized by the opening of K+ channels. The hyperpolarization causes Ca2+ influx and vasodilatation.

The EDRF has not been identified. It may be:

    1. epoxyeicosatetraenoic acids (EETs),
    2. endogenous cannabinoid (anandamide),
    3.  hydroxyl radicals,
    4. O2-
    5. K+

The currently available data suggest that it is most probably an EET.

NO has effects on the large blood vessels (>300 µm), while EDFH has effects on the smaller blood vessels (<300 µm).