The effect of thromboxane on contraction of canine mesenteric and lingual arteries.
Thromboxane A2 (TXA2), a potent vasoconstrictor agent, is released from platelets and smooth muscle during inflammation and trauma. TXA2 may cause lingual artery (LA) contraction, leading to lingual paresthesia. The effects of U-46619, a TxA2 mimetic, on isolated rings of canine LA and mesenteric artery (MA) were examined. U-46619 (1 nmol/L to 1 mumol/L) caused a triphasic contraction of LA and MA; a rapid, phasic contraction; a slow, sustained contraction; and, upon washout of U-46619, a maintained contraction. The MA relaxed slowly, but the LA remained contracted for at least three h after washout. Decreasing extracellular calcium ion (Ca2+o) to less than 0.1 mumol/L with 2 mmol/L EGTA relaxed MA, but not LA. EGTA (4 mmol/L) partially relaxed the maintained contraction of LA. Inhibition of protein kinase C with amphotericin B or staurosporine inhibited the phasic and sustained contractions of LA, but did not affect the maintained contraction in the presence or absence of EGTA. Thus, CA2+o was required for the initial contraction of the LA by U-46619, but did not appear to be required for the maintained contraction following washout of U-46619. The data support the conclusion that following a brief exposure to U-46619, maintained contraction of LA persists by a unique mechanism that may be independent of Ca2+ and protein kinase C. Sustained LA contraction after exposure to endogenous TXA2 during inflammation and trauma may contribute to impaired lingual blood flow and orofacial tissue injury.
Greenberg
S S
SS
LSU Medical Center, Department of Medicine, New Orleans 70112.
Wang
Y
Y
Xie
J
J
Smartz
L
L
Rammazatto
L
L
Curro
F A
FA
D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; D000818:Animals; D002118:Calcium / Q000502:physiology; D004285:Dogs; D004533:Egtazic Acid / Q000494:pharmacology; D004730:Endothelium, Vascular / Q000187:drug effects / Q000502:physiology*; D005260:Female; D016014:Linear Models; D008297:Male; D008638:Mesenteric Arteries / Q000187:drug effects* / Q000502:physiology; D009638:Norepinephrine; D011189:Potassium Chloride; D011450:Prostaglandin Endoperoxides, Synthetic / Q000494:pharmacology; D011493:Protein Kinase C / Q000037:antagonists & inhibitors; D013928:Thromboxane A2 / Q000031:analogs & derivatives / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D014059:Tongue / Q000098:blood supply*; D014661:Vasoconstriction / Q000187:drug effects* / Q000502:physiology; D014662:Vasoconstrictor Agents / Q000494:pharmacology
D011450:Prostaglandin Endoperoxides, Synthetic; D014662:Vasoconstrictor Agents; D004533:Egtazic Acid; D013928:Thromboxane A2; D011189:Potassium Chloride; D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; D011493:Protein Kinase C; D002118:Calcium; D009638:Norepinephrine