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Thromboxane-induced pulmonary vasoconstriction: involvement of calcium
Journal of Applied Physiology (Bethesda, Md. : 1985)
|January 1, 1985
Summary
Tert-butyl hydroperoxide and arachidonic acid trigger thromboxane B2 production and pulmonary vasoconstriction in rabbits. Thromboxane B2 induces vasoconstriction by increasing intracellular calcium levels.
Area of Science:
- Cardiovascular Physiology
- Pulmonary Circulation
- Eicosanoid Metabolism
Background:
- Pulmonary vasoconstriction is a critical physiological response.
- Thromboxane B2 (TxB2) is a potent vasoconstrictor.
- The precise mechanisms of TxB2-induced pulmonary vasoconstriction require further elucidation.
Purpose of the Study:
- To investigate the role of thromboxane B2 in pulmonary vasoconstriction.
- To determine the signaling pathways involved in thromboxane-induced pulmonary vasoconstriction.
Main Methods:
- Infusion of tert-butyl hydroperoxide (t-bu-OOH) or arachidonic acid into rabbit pulmonary arteries.
- Measurement of thromboxane B2 production and pulmonary arterial pressure.
- Administration of cyclooxygenase inhibitors, thromboxane synthase inhibitors, calcium entry blockers, and calmodulin inhibitors.
Main Results:
- Both t-bu-OOH and arachidonic acid stimulated TxB2 production and pulmonary vasoconstriction.
- Inhibition of cyclooxygenase or thromboxane synthase blocked these effects.
- Calcium entry blockers and calmodulin inhibitors prevented thromboxane-induced vasoconstriction, with calmodulin inhibitors not affecting TxB2 production.
Conclusions:
- Thromboxane B2 plays a significant role in mediating pulmonary vasoconstriction.
- The vasoconstrictive effects of thromboxane are dependent on calcium influx.
- Calmodulin appears to be involved in the downstream signaling of thromboxane-induced pulmonary vasoconstriction.