Ca2+-channel current and its modification by the dihydropyridine agonist BAY k 8644 in isolated smooth muscle cells

1986 ◽  
Vol 406 (3) ◽  
pp. 259-265 ◽  
Author(s):  
G. Droogmans ◽  
G. Callewaert
Keyword(s):  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Muscle Cells ◽  
Bay K 8644 ◽  
Channel Current ◽  
Isolated Smooth Muscle Cells

14,15-Dihydroxyeicosatrienoic acid relaxes bovine coronary arteries by activation of KCa channels

2002 ◽  
Vol 282 (5) ◽  
pp. H1656-H1664 ◽  
Author(s):  
William B. Campbell ◽  
Christine Deeter ◽  
Kathryn M. Gauthier ◽  
Richard H. Ingraham ◽  
J. R. Falck ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Coronary Arteries ◽  
Epoxide Hydrolase ◽  
Muscle Cells ◽  
Kca Channels ◽  
Vasodilator Activity ◽  
Inside Out ◽  
Isolated Smooth Muscle Cells

Epoxyeicosatrienoic acids (EETs) cause vascular relaxation by activating smooth muscle large conductance Ca2+-activated K+ (KCa) channels. EETs are metabolized to dihydroxyeicosatrienoic acids (DHETs) by epoxide hydrolase. We examined the contribution of 14,15-DHET to 14,15-EET-induced relaxations and characterized its mechanism of action. 14,15-DHET relaxed U-46619-precontracted bovine coronary artery rings but was approximately fivefold less potent than 14,15-EET. The relaxations were inhibited by charybdotoxin, iberiotoxin, and increasing extracellular K+ to 20 mM. In isolated smooth muscle cells, 14,15-DHET increased an iberiotoxin-sensitive, outward K+ current and increased KCa channel activity in cell-attached patches and inside-out patches only when GTP was present. 14,15-[14C]EET methyl ester (Me) was converted to 14,15-[14C]DHET-Me, 14,15-[14C]DHET, and 14,15-[14C]EET by coronary arterial rings and endothelial cells but not by smooth muscle cells. The metabolism to 14,15-DHET was inhibited by the epoxide hydrolase inhibitors 4-phenylchalcone oxide (4-PCO) and BIRD-0826. Neither inhibitor altered relaxations to acetylcholine, whereas relaxations to 14,15-EET-Me were increased slightly by BIRD-0826 but not by 4-PCO. 14,15-DHET relaxes coronary arteries through activation of KCa channels. Endothelial cells, but not smooth muscle cells, convert EETs to DHETs, and this conversion results in a loss of vasodilator activity.

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