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Direct effects of streptokinase on the isolated rat myocardium
Insights
Streptokinase infusion did not significantly alter mechanical function or enzyme release in normal or ischemic rat hearts. However, it reduced nucleoside release in post-ischemic hearts, suggesting a protective effect.
Area of Science:
- Cardiovascular Pharmacology
- Thrombolytic Therapy Research
Background:
- Streptokinase is a widely used thrombolytic agent for myocardial infarction.
- Its direct effects on cardiac function and cellular integrity require further elucidation.
Purpose of the Study:
- To evaluate the impact of streptokinase infusion on the mechanical function of normal and globally ischemic isolated rat hearts.
- To assess streptokinase's effects on cellular membrane integrity via enzyme and nucleoside release.
Main Methods:
- Isolated rat hearts (normal and globally ischemic) were infused with either buffer or streptokinase.
- Mechanical function was monitored.
- Release of lactate dehydrogenase (LDH), creatine kinase (CK), and nucleosides into coronary effluents was measured.
Main Results:
- Streptokinase infusion did not significantly affect mechanical function or LDH/CK release in normal or ischemic hearts compared to buffer.
- A significant increase in nucleoside release was observed during streptokinase infusion in normal hearts.
- In post-ischemic hearts, streptokinase infusion resulted in a twofold increase in nucleoside release, compared to a sixfold increase with buffer.
Conclusions:
- Streptokinase does not impair the mechanical function or cellular integrity of normal or ischemic rat hearts.
- Streptokinase may offer a protective effect in post-ischemic conditions by reducing nucleoside release.
Abstract:
The utilization of streptokinase as a thrombolytic agent is prevalent in the management of patients following a myocardial infarction. The present investigation was designed to assess the direct effects of streptokinase infusion on the normal isolated rat heart and on the globally ischemic isolated rat heart. The effects of streptokinase on the mechanical function of the hearts were monitored, as well as the effects on the membrane integrity of the cells, as indicated by enzyme release. The normal hearts were infused with either buffer or streptokinase. Both the normal and streptokinase-treated normal hearts exhibited a decrease in function during the course of each experiment. Under these conditions, there were no significant differences in the values for mechanical function in either group. The release of lactate dehydrogenase (LDH) and creatine kinase (CK) into the coronary effluents was not significantly increased during the infusion of streptokinase. There was a significant increase in the release of nucleosides during the streptokinase infusion period compared with the buffer infusion period. The infusion of either buffer or streptokinase was compared in the preischemic and postischemic rat heart. The values obtained during preischemic infusion with buffer or streptokinase were comparable to the values obtained in the normal and streptokinase-treated normal hearts. There were no significant differences in the values for mechanical function measured during buffer infusion following ischemia compared with those measured during streptokinase infusion following ischemia. In the postischemic hearts, there was a sixfold increase in the release of nucleosides during buffer infusion, whereas only a twofold increase was observed in the postischemic hearts during streptokinase infusion.(ABSTRACT TRUNCATED AT 250 WORDS)