A thromboxane A(2) system in the Atlantic stingray, Dasyatis sabina

Gen Comp Endocrinol. 2003 Feb 1;130(2):157-64. doi: 10.1016/s0016-6480(02)00586-5.


Thromboxane B(2)(TXB(2)) is the stable metabolite of thromboxane A(2)(TXA(2)) and thromboxane B(2)-like immunoreactivity (iTXB(2)) has been identified in the plasma of the Atlantic stingray, Dasyatis sabina (0.57+/-0.03 ng/ml). Plasma levels of iTXB(2) increase if the blood is allowed to clot (3.0+/-0.27 ng/ml). When clotting occurs in the presence of indomethacin, this increase is partially inhibited (1.5+/-0.17 ng/ml), indicating the presence of a cyclooxygenase activity. Radioligand binding analysis using the TXA(2) analog [125I]BOP in isolated kidney membranes revealed a receptor of K(d)=2.88+/-0.51 nM and B(max)=25.6+/-5.9 fmol/mg protein. [125I]BOP binding was displaced by the TXA(2) receptor (TP receptor) agonists U46619 (IC(50)=106.4+/-15.7 nM) and U44069 (IC(50)=88.7+/-13.0 nM), and the antagonist SQ29548 (IC(50)=51.0+/-12.9 nM). Binding was also displaced stereoselectively by the antagonists (-)L657925 (IC(50)=18.9+/-3.8 nM) and (+)L657926 (IC(50)=2025+/-280 nM). Tissue bath studies revealed that U46619, a stable TXA(2) mimetic, elicited concentration-dependent contractions in the ventral aorta which were inhibited in a concentration-dependent manner by the TP receptor antagonist SQ29548. Using a human TP receptor riboprobe, Northern blotting of mRNA isolated from the stingray kidney identified transcripts of 2.8 and 6kb. The 2.8kb transcript is similar to a 2.8kb transcript found in human cells or tissues, but the 6kb transcript may be unique. These data indicate the presence of a TXB(2)-like substance in the blood, a TP receptor in the kidney, TXA(2) biological activity in the ventral aorta, and expression of a TP receptor-like gene.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Aorta / drug effects
  • Aorta / metabolism*
  • Cyclooxygenase Inhibitors / pharmacology
  • Elasmobranchii / physiology*
  • Female
  • In Vitro Techniques
  • Indomethacin / pharmacology
  • Kidney / drug effects
  • Kidney / metabolism*
  • Male
  • Muscle Contraction / physiology
  • Muscle, Smooth / drug effects
  • Muscle, Smooth / metabolism
  • Receptors, Thromboxane / metabolism
  • Thromboxane A2 / blood
  • Thromboxane A2 / metabolism*
  • Thromboxane B2 / blood
  • Thromboxane B2 / metabolism*


  • Cyclooxygenase Inhibitors
  • Receptors, Thromboxane
  • Thromboxane B2
  • Thromboxane A2
  • Indomethacin