Jv. Mombouli et al., BIOASSAY OF ENDOTHELIUM-DERIVED HYPERPOLARIZING FACTOR, Biochemical and biophysical research communications, 221(2), 1996, pp. 484-488
Endothelium-derived hyperpolarizing factor (EDHF) mediates vasodilatat
ion in certain blood vessels, together with prostacyclin and NO. Howev
er, its chemical nature is not known. A perfusion-superfusion cascade
was developed to confirm the diffusible nature of EDHF. Canine carotid
arteries with endothelium were used as donors of vasoactive substance
s, whereas rings of coronary artery without endothelium were used as d
etectors. Inhibitors of NO synthesis and cyclooxygenase were present t
hroughout, to avoid interference from NO and prostanoids. Measurements
of membrane potential and isometric tension, in coronary arteries wit
hout endothelium (used as detectors), demonstrated the release of EDHF
from the carotid arteries, following treatment with 8-methoxypsoralen
, bradykinin and thimerosal. The K+-channel blocker tetraethylammonium
inhibited the action of EDHF in the detectors. Thus, these results de
monstrate that endothelial cells release a diffusible activator of K+-
channels in vascular smooth muscle. (C) 1996 Academic Press, Inc.