RESUMO
Statins have a beneficial effect after myocardial infarction, but the relationship between glucose transporters and their use before the event has not yet been studied. We assessed the effects of atorvastatin treatment pre- and post-myocardial infarction on cardiovascular function and glucose transporter 4 (GLUT4) in the heart. Wistar-Kyoto rats were treated with 20 mg/kg atorvastatin or vehicle for 14 days before coronary artery occlusion surgery (myocardial infarction) or sham surgery. Echocardiographic evaluations were carried out 48 h after myocardial infarction (protocol A) and after 7 days (protocol B), when atorvastatin was also administered. Plasma inflammatory markers and GLUT4 in the heart were also evaluated. Animals were divided into the following groups: sham-operated and vehicle (C), myocardial infarction and vehicle (I), sham-operated and atorvastatin (CAt) and myocardial infarction and atorvastatin (IAt). After 48 h, myocardial infarction induced higher left ventricular fractional shortening in IAt versus I (~ 60%, P = 0.036), and the ejection fraction was lower (protocol A ~ 37%; protocol B ~ 30%). Myocardial infarction was associated with a rise in plasma membrane GLUT4 after 48 h (~ 40%, P < 0.001), and a reduction in GLUT4 after 7 days (I 25%; IAt 49%, P < 0.001). Atorvastatin treatment for 48 h after the infarction did not change GLUT4 expression, and after 7 days it had an additional negative effect on GLUT4 content (~ 39%, P = 0.030). In conclusion, atorvastatin treatment pre- and post-myocardial infarction improved myocardial contractility after 48 h, but not after 7 days, and was not associated with an increase in GLUT4 expression.
Assuntos
Ventrículos do Coração/efeitos dos fármacos , Ácidos Heptanoicos/farmacologia , Contração Muscular/efeitos dos fármacos , Infarto do Miocárdio/tratamento farmacológico , Infarto do Miocárdio/metabolismo , Pirróis/farmacologia , Animais , Atorvastatina , Ecocardiografia/métodos , Transportador de Glucose Tipo 4/metabolismo , Ventrículos do Coração/metabolismo , Masculino , Miocárdio/metabolismo , Ratos , Ratos Endogâmicos WKY , Remodelação Ventricular/efeitos dos fármacosRESUMO
AIM: Investigate, in healthy sedentary rats, the potential mechanisms involved on the effects of beta hydroxy beta methylbutyrate (HMB) supplementation upon the glycaemic homeostasis, by evaluating the insulin sensitivity in liver, skeletal muscle, and white adipose tissue. METHODS: Rats were supplemented with either beta hydroxy beta methylbutyrate (320 mg kg(-1) BW) or saline by gavage for 4 weeks. After the experimental period, the animals were subjected to the glucose tolerance test (GTT) and plasma non-esterified fatty acids (NEFA) concentration measurements. The soleus skeletal muscle, liver and white adipose tissue were removed for molecular (western blotting and RT-PCR) and histological analysis. RESULTS: The beta hydroxy beta methylbutyrate supplemented rats presented: (i) higher ratio between the area under the curve (AUC) of insulinaemia and glycaemia during glucose tolerance test; (ii) impairment of insulin sensitivity on liver and soleus skeletal muscle after insulin overload; (iii) reduction of glucose transporter 4 (GLUT 4) total and plasma membrane content on soleus; (iv) increased hormone-sensitive lipase (HSL) mRNA and protein expression on white adipose tissue and plasma NEFA levels and (v) reduction of fibre cross-sectional area of soleus muscle. CONCLUSION: The data altogether indicate that beta hydroxy beta methylbutyrate supplementation impairs insulin sensitivity in healthy sedentary rats, which, in the long-term, could lead to an increased risk of developing type 2 diabetes.