Plasma-mediated potentiation in prostanoid-induced contractions in isolated canine external jugular veins.
We examined the effects of plasma on contractile responses of isolated dog external jugular veins to a thromboxane A(2) analog, U46619, and noradrenaline. Pretreatment with 1.0% plasma in Krebs-bicarbonate solution, but not 0.1%, caused a significant left and upward shift in the concentration-contractile response curve for U46619. The plasma-mediated potentiation of the response to U46619 was found in the venous segments without intact endothelium. The administration of 2x10(-5) M lysophosphatidylcholine in Krebs-bicarbonate solution with no plasma also produced a significant left and upward shift of the concentration-contractile response curve for U46619, the shift being quite similar to that obtained with 1.0% plasma. In contrast, pretreatment with 1.0% plasma or 2x10(-5) M lysophosphatidylcholine produced no significant effect on the noradrenaline-mediated contractions in the venous segments. Pretreatment with 10(-4) M L-ascorbate or 0.1 mg/ml alpha-tocopherol in the presence of 1.0% plasma caused a significant reduction in the plasma-mediated potentiation of the contractile responses to U46619. These findings suggest that lysophosphatidylcholine, a major phospholipid component of oxidized low-density lipoproteins, may contribute, in part, to the plasma-mediated potentiation of contractile responses of the isolated veins to U46619, and that the antioxidant vitamin, L-ascorbate, or alpha-tocopherol significantly reduces the plasma-mediated potentiation of the contractile responses to U46619, which may be related to inhibiting the production of lysophosphatidylcholine in plasma.
Shibata
Tatsuhiko
T
1st Department of Physiology, Shinshu University School of Medicine, Matsumoto, 390-8621 Japan.
Ikomi
Fumitaka
F
Ohhashi
Toshio
T
D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid / Q000494:pharmacology; D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D001205:Ascorbic Acid / Q000494:pharmacology; D001790:Blood Physiological Phenomena; D004285:Dogs; D005260:Female; D066298:In Vitro Techniques; D007601:Jugular Veins / Q000187:drug effects* / Q000502:physiology*; D008244:Lysophosphatidylcholines / Q000494:pharmacology; D008297:Male; D009638:Norepinephrine / Q000494:pharmacology; D011188:Potassium / Q000494:pharmacology; D011453:Prostaglandins / Q000494:pharmacology*; D014661:Vasoconstriction / Q000187:drug effects / Q000502:physiology*; D014662:Vasoconstrictor Agents / Q000494:pharmacology; D024502:alpha-Tocopherol / Q000494:pharmacology
D000975:Antioxidants; D008244:Lysophosphatidylcholines; D011453:Prostaglandins; D014662:Vasoconstrictor Agents; D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; D024502:alpha-Tocopherol; D001205:Ascorbic Acid; D011188:Potassium; D009638:Norepinephrine