Tension cost correlates with mechanical and biochemical parameters in different myocardial contractility conditions
| Autor: | Dalton Valentim Vassallo, Luis Vestena, Eduardo Frizzera Meira, Alessandra Simão Padilha, Cleci Menezes Moreira, Ivanita Stefanon |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2012 |
| Předmět: |
Male
medicine.medical_specialty Myosin ATPase Myocardial Infarction Infarction Isometric exercise Nephrectomy Rats Inbred WKY Ventricular Function Left Diabetes Mellitus Experimental Contractility Ventricular Myosins Internal medicine Diabetes mellitus Rats Inbred SHR medicine Animals Myocardial infarction Enzyme Inhibitors Desoxycorticosterone Papillary muscle lcsh:R5-920 Chemistry Diabetes General Medicine Papillary Muscles medicine.disease Myocardial Contraction Pathophysiology Rats Endocrinology medicine.anatomical_structure NG-Nitroarginine Methyl Ester Basic Research Hypertension lcsh:Medicine (General) |
| Zdroj: | Clinics, Volume: 67, Issue: 5, Pages: 489-496, Published: 2012 Clinics; v. 67 n. 5 (2012); 489-496 Clinics; Vol. 67 Núm. 5 (2012); 489-496 Clinics; Vol. 67 No. 5 (2012); 489-496 Clinics Universidade de São Paulo (USP) instacron:USP Clinics, Vol 67, Iss 5, Pp 489-496 (2012) |
| ISSN: | 1980-5322 1807-5932 |
| Popis: | OBJECTIVES: Tension cost, the ratio of myosin ATPase activity to tension, reflects the economy of tension development in the myocardium. To evaluate the mechanical advantage represented by the tension cost, we studied papillary muscle contractility and the activity of myosin ATPase in the left ventricles in normal and pathophysiological conditions. METHODS: Experimental protocols were performed using rat left ventricles from: (1) streptozotocin-induced diabetic and control Wistar rats; (2) N-nitro-L-arginine methyl ester (L-NAME) hypertensive and untreated Wistar rats; (3) deoxycorticosterone acetate (DOCA) salt-treated, nephrectomized and salt- and DOCA-treated rats; (4) spontaneous hypertensive rats (SHR) and Wistar Kyoto (WKY) rats; (5) rats with myocardial infarction and sham-operated rats. The isometric force, tetanic tension, and the activity of myosin ATPase were measured. RESULTS: The results obtained from infarcted, diabetic, and deoxycorticosterone acetate-salt-treated rats showed reductions in twitch and tetanic tension compared to the control and sham-operated groups. Twitch and tetanic tension increased in the N-nitro-L-arginine methyl ester-treated rats compared with the Wistar rats. Myosin ATPase activity was depressed in the infarcted, diabetic, and deoxycorticosterone acetate salt-treated rats compared with control and sham-operated rats and was increased in N-nitro-L-arginine methyl ester-treated rats. These parameters did not differ between SHR and WKY rats. In the studied conditions (e.g., post-myocardial infarction, deoxycorticosterone acetate salt-induced hypertension, chronic N-nitro-L-arginine methyl ester treatment, and streptozotocin-induced diabetes), a positive correlation between force or plateau tetanic tension and myosin ATPase activity was observed. CONCLUSION: Our results suggest that the myocardium adapts to force generation by increasing or reducing the tension cost to maintain myocardial contractility with a better mechanical advantage. |
| Databáze: | OpenAIRE |
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