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Salutary actions of thromboxane synthetase inhibition during global myocardial ischemia
Insights
The thromboxane synthetase inhibitor OKY-1581 protected cat hearts during ischemia and reperfusion. This drug reduced cellular damage and improved cardiac function, suggesting thromboxanes contribute to ischemia-induced injury.
Area of Science:
- Cardiovascular Research
- Biochemistry
- Pharmacology
Background:
- Ischemia-reperfusion injury is a significant clinical problem.
- Thromboxanes are implicated in myocardial damage during ischemia.
Purpose of the Study:
- To investigate the protective effects of the thromboxane synthetase inhibitor OKY-1581 on isolated cat hearts subjected to ischemia-reperfusion.
- To determine the role of thromboxanes in myocardial cellular damage.
Main Methods:
- Isolated cat hearts were perfused with Krebs-Henseleit solution.
- Ischemia was induced by reducing perfusion, followed by reperfusion.
- Hearts were treated with the thromboxane synthetase inhibitor OKY-1581.
- Cardiac contractile force, coronary vascular resistance, creatine kinase (CK) activity, and cathepsin D activity were measured.
Main Results:
- OKY-1581 treatment prevented increases in circulating thromboxane B2.
- Reperfusion resulted in higher cardiac contractile force in OKY-1581 treated hearts.
- OKY-1581 treated hearts showed lower coronary vascular resistance, preserved cellular integrity (higher CK activity), and improved lysosomal stability (lower cathepsin D activity).
Conclusions:
- Thromboxane synthetase inhibition with OKY-1581 protects the heart against ischemia-reperfusion injury.
- Thromboxanes play a significant role in propagating myocardial cellular damage during ischemia.
- OKY-1581 demonstrates potential therapeutic value in mitigating ischemia-reperfusion damage.
Abstract:
Isolated cat hearts were perfused with blood-free Krebs-Henseleit solution for 165 min. Ischemia was induced by reducing perfusion to 0.02 ml/min/g wet heart weight for 2 h followed by reperfusion at controls flows for 30 min. Hearts perfused with the thromboxane synthetase inhibitor OKY-1581 at concentrations of 5 X 10(-6) M were spared from the increases in circulating thromboxane B2 occurring in untreated ischemic hearts. After reperfusion, cardiac contractile force increased to a higher level in OKY-1581 treated hearts. This was associated with a lower coronary vascular resistance than in untreated ischemic hearts. OKY-1581 treated ischemic hearts exhibited lower perfusate and higher myocardial creatine kinase (CK) activity than untreated ischemic hearts, indicative of preservation of cellular integrity. Also, OKY-1581 treated ischemic hearts showed improved lysosomal stability as evidenced by a lower tissue percent free cathepsin D activity than untreated ischemic hearts. These results are consistent with a significant role of thromboxanes in the propagation of myocardial cellular damage during ischemia.