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Lack of a significant protective effect of augmented circulating glucose on the ischemic myocardium.BJ
Insights
Glucose and insulin infusions did not protect cats from heart damage during acute myocardial ischemia. While they aided in clearing creatine phosphokinase (CPK) and inhibiting proteolysis, these effects did not reduce infarct size.
Area of Science:
- Cardiology
- Biochemistry
- Physiology
Background:
- Acute myocardial ischemia poses a significant threat to cardiac function.
- Glucose and insulin are commonly investigated for their potential cardioprotective effects.
- Understanding their impact on myocardial infarct development is crucial.
Purpose of the Study:
- To investigate the effects of glucose and insulin infusion on hemodynamic responses during acute myocardial ischemia in cats.
- To determine if glucose and insulin offer a protective effect against myocardial infarct development.
- To explore the influence of glucose and insulin on plasma creatine phosphokinase (CPK) levels and proteolysis during ischemia.
Main Methods:
- Cats were subjected to acute myocardial ischemia induced by coronary artery ligation.
- Infusions of glucose alone or glucose with insulin were administered.
- Hemodynamic parameters were monitored.
- Myocardial creatine phosphokinase (CPK) activity and plasma CPK levels were assessed.
- Proteolysis was evaluated during the early phase of ischemia.
Main Results:
- Glucose or glucose with insulin infusion did not alter the hemodynamic response to coronary artery ligation.
- No protective effect of glucose and insulin was observed on myocardial infarct status.
- Glucose and insulin promoted plasma CPK clearance and inhibited proteolysis during early ischemia.
Conclusions:
- Glucose and insulin do not diminish the spread of ischemic damage or limit infarct extension in the context of acute myocardial ischemia.
- The observed effects on CPK clearance and proteolysis may represent a generalized adaptive response to ischemic stress.
- These metabolic interventions do not provide direct cardioprotection against evolving infarcts.
Abstract:
Infusion of glucose alone or glucose with insulin in cats subjected to acute myocardial ischemia did not alter the hemodynamic response of the cats to coronary artery ligation. Furthermore, determination of myocardial creatine phosphokinase (CPK) (ATP:creatine N-phosphotransferase, EC 2.7.3.2) activities failed to reveal a protective effect of glucose and insulin upon the status of the developing infarct in the ischemic myocardium. However, glucose and insulin apparently promote clearance of CPK from the plasma and inhibit proteolysis during the early phase of myocardial ischemia. These actions may be of value in generalized adaptive response of the animal to the stress of ischemia, but does not per se appear to diminish the spread of the ischemic damage within the heart not to limit the extension of the evolving infarct.