Role of eicosanoids in alteration of membrane electrical properties in isolated mesenteric arteries of salt-loaded, Dahl salt-sensitive rats.
1. The role of eicosanoids in altered membrane electrical properties of Dahl salt-sensitive (DS) rats was investigated, by use of conventional microelectrodes technique, in isolated superior mesenteric arteries of DS rats and Dahl salt-resistant (DR) rats fed either a high or low salt diet. 2. The membrane was significantly depolarized in salt-loaded DS rats compared with the other three groups. In addition, the arteries of salt-loaded DS rats exhibited spontaneous electrical activity. 3. Spontaneous electrical activity in salt-loaded DS rats was inhibited by the following: indomethacin, a cyclo-oxygenase inhibitor; ONO-3708, a prostaglandin H2/thromboxane A2 receptor antagonist; OKY-046, a thromboxane A2 synthase inhibitor; nicardipine, a Ca(2+)-channel antagonist and by Ca(2+)-free solution. In addition, spontaneous electrical activity was enhanced by a thromboxane A2 analogue and by prostaglandin H2. Spontaneous electrical activity was unaffected by phentolamine, atropine and tetrodotoxin. 4. Membrane potential in arteries of salt-loaded DS rats was not affected by either indomethacin or ONO-3708. 5. Spontaneous contraction, sensitive to indomethacin, was present, and contractile sensitivity to high potassium solution was enhanced in arteries of salt-loaded DS rats. 6. These findings suggest that eicosanoid action, together with membrane depolarization, may lead to the activation of voltage-dependent Ca(2+)-channels, thereby causing spontaneous electrical activity in mesenteric arteries of salt-loaded DS rats. In addition, tension data suggest that these changes in membrane properties are related to enhanced contractile activities in salt-loaded DS rats. Mechanisms of depolarization remain to be determined.
Fujii
K
K
Second Department of Internal Medicine,Faculty of Medicine, Kyushu University, Fukuoka, Japan.
Onaka
U
U
Ohya
Y
Y
Ohmori
S
S
Tominaga
M
M
Abe
I
I
Takata
Y
Y
Fujishima
M
M
D000818:Animals; D015777:Eicosanoids / Q000502:physiology*; D066298:In Vitro Techniques; D008297:Male; D008564:Membrane Potentials / Q000502:physiology*; D008638:Mesenteric Arteries / Q000502:physiology*; D009119:Muscle Contraction / Q000502:physiology; D051381:Rats; D012965:Sodium Chloride
D015777:Eicosanoids; D012965:Sodium Chloride