Relationship Between Antihypertensive Drugs and Metabolic Syndrome

Cardioprotective effect of ranolazine in nondiabetic and diabetic male rats subjected to isoprenaline-induced acute myocardial infarction involves modulation of AMPK and inhibition of apoptosis

Diabetes increases the sensitivity of myocardium to ischemic damage and impairs response of the myocardium to cardioprotective interventions. The present study aimed to elucidate the potential cardioprotective effect provided by ranolazine during myocardial infarction in nondiabetic and diabetic male rats. As AMP-activated protein kinase (AMPK) has been shown to be involved in the cellular response to ischemic injury, in this context, the present animal study evaluated the modulating role of ranolazine in the AMPK expression in isoprenaline-induced myocardial ischemic rat model. Male rats were divided into 2 experiments: experiment I and II (nondiabetic and diabetic rats) and assigned to normal control, saline control for isoprenaline, isoprenaline control, and ranolazine-treated groups. Ranolazine administration revealed effectiveness in attenuating the severity of isoprenaline-induced myocardial injury in both nondiabetic and diabetic rats as revealed by ECG signs, histopathological score, and apoptotic markers via abrogating the increments in the inflammatory and oxidative stress markers and modulating AMPK expression. Therefore, the current cardioprotective effect of ranolazine was, at least in part, mediated through inhibition of apoptosis and modulation of AMPK expression, encouraging considering the utility of ranolazine in protection from acute myocardial infarction.

Ranolazine increases β-cell survival and improves glucose homeostasis in low-dose streptozotocin-induced diabetes in mice

In addition to its anti-ischemic and antianginal effects, ranolazine has been shown to lower hemoglobin A(1c) (HbA(1c)) in patients with coronary artery disease and diabetes. The present study was undertaken to test the hypothesis that ranolazine lowers HbA(1c) because of improved glucose homeostasis in an animal model. Diabetes in mice was induced by giving multiple low doses of streptozotocin. Ranolazine was given twice daily via an oral gavage (20 mg/kg) for 8 weeks. Fasting plasma glucose levels were significantly lower in the ranolazine-treated group (187 ± 19 mg/dl) compared with the vehicle group (273 ± 23 mg/dl) at 8 weeks. HbA(1c) was 5.8 ± 0.4% in the vehicle group and 4.5 ± 0.2% in the ranolazine-treated group (p < 0.05). Glucose disposal during the oral glucose tolerance test (OGTT) and insulin tolerance test were not different between the two groups; however, during OGTT, peak insulin levels were significantly (p < 0.05) higher in ranolazine-treated mice. Mice treated with ranolazine had healthier islet morphology and significantly (p < 0.01) higher β-cell mass (69 ± 2% per islet) than the vehicle group (50 ± 5% per islet) as determined from hematoxylin and eosin staining. The number of apoptotic cells was significantly (p < 0.05) less in the pancreas of the ranolazine-treated group (14 ± 2% per islet) compared with the vehicle group (24 ± 4% per islet). In addition, ranolazine increased glucose-stimulated insulin secretion in rat and human islets in a glucose-dependent manner. These data suggest that ranolazine may be a novel antidiabetic agent that causes β-cell preservation and enhances insulin secretion in a glucose-dependent manner in diabetic mice.