Myocardial performance in conscious streptozotocin diabetic rats
| Autor: | Giulianna R. Borges, Helio Cesar Salgado, Mauro de Oliveira, Rubens Fazan |
|---|---|
| Rok vydání: | 2006 |
| Předmět: |
Blood Glucose
Male lcsh:Diseases of the circulatory (Cardiovascular) system medicine.medical_specialty Mean arterial pressure Endocrinology Diabetes and Metabolism medicine.medical_treatment Hemodynamics Blood Pressure Ventricular Function Left Diabetes Mellitus Experimental Contractility Dobutamine Internal medicine Heart rate medicine Animals Rats Wistar Original Investigation business.industry Insulin Body Weight Heart Streptozotocin Myocardial Contraction Rats Endocrinology lcsh:RC666-701 Cardiology Ventricular pressure Receptors Adrenergic beta-1 Cardiology and Cardiovascular Medicine business Diabetic Angiopathies medicine.drug |
| Zdroj: | Cardiovascular Diabetology, Vol 5, Iss 1, p 26 (2006) Cardiovascular Diabetology |
| ISSN: | 1475-2840 |
| Popis: | Background In spite of a large amount of studies in anesthetized animals, isolated hearts, and in vitro cardiomyocytes, to our knowledge, myocardial function was never studied in conscious diabetic rats. Myocardial performance and the response to stress caused by dobutamine were examined in conscious rats, fifteen days after the onset of diabetes caused by streptozotocin (STZ). The protective effect of insulin was also investigated in STZ-diabetic rats. Methods Cardiac contractility and relaxation were evaluated by means of maximum positive (+dP/dtmax) and negative (-dP/dtmax) values of first derivative of left ventricular pressure over time. In addition, it was examined the myocardial response to stress caused by two dosages (1 and 15 μg/kg) of dobutamine. One-way analysis of variance (ANOVA) was used to compare differences among groups, and two-way ANOVA for repeated measure, followed by Tukey post hoc test, to compare the responses to dobutamine. Differences were considered significant if P < 0.05. Results Basal mean arterial pressure, heart rate, +dP/dtmax and -dP/dtmax were found decreased in STZ-diabetic rats, but unaltered in control rats treated with vehicle and STZ-diabetic rats treated with insulin. Therefore, insulin prevented the hemodynamic and myocardial function alterations observed in STZ-diabetic rats. Lower dosage of dobutamine increased heart rate, +dP/dtmax and -dP/dtmax only in STZ-diabetic rats, while the higher dosage promoted greater, but similar, responses in the three groups. In conclusion, the results indicate that myocardial function was remarkably attenuated in conscious STZ-diabetic rats. In addition, the lower dosage of dobutamine uncovered a greater responsiveness of the myocardium of STZ-diabetic rats. Insulin preserved myocardial function and the integrity of the response to dobutamine of STZ-diabetic rats. Conclusion The present study provides new data from conscious rats showing that the cardiomyopathy of this pathophysiological condition was expressed by low indices of contractility and relaxation. In addition, it was also demonstrated that these pathophysiological features were prevented by the treatment with insulin. |
| Databáze: | OpenAIRE |
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