dihydropyridines and Glucose-Intolerance

Azelnidipine is a unique dihydropyridine calcium channel blocker with selectivity for L-type calcium channels that has been launched for the treatment of hypertension. Azelnidipine exhibits long-acting blood pressure-lowering effects without increasing heart rate. High blood pressure is associated with many metabolic disorders, including glucose intolerance and insulin resistance. Antihypertensive medications that interfere with various steps in the renin-angiotensin system improve glucose tolerance and insulin resistance; however, the effects of calcium channel blockers on glucose metabolism and insulin resistance remain controversial. Recent studies have demonstrated that azelnidipine could improve insulin resistance and glucose tolerance by potentially inhibiting sympathetic nerve activity. In addition, azelnidipine exhibits anti-inflammatory and anti-oxidative effects, suggesting that it is a beneficial antihypertensive agent with anti-atherogenic and cardioprotective effects for the treatment of not only hypertensive patients with glucose intolerance, but also those with metabolic disorders.

Topics: Azetidinecarboxylic Acid; Calcium Channel Blockers; Dihydropyridines; Glucose Intolerance; Humans; Hypertension; Metabolic Diseases; Renin-Angiotensin System

The potential combined effect and mechanism of calcium channel blockers (CCB) and angiotensin II type 1 receptor blockers (ARB) to improve insulin resistance were investigated in type 2 diabetic KK-Ay mice, focusing on their antioxidative action. Treatment of KK-Ay mice with a CCB, azelnidipine (3 mg/kg/day), or with an ARB, olmesartan (3 mg/kg/day), for 2 weeks lowered the plasma concentrations of glucose and insulin in the fed state, attenuated the increase in plasma glucose in the oral glucose tolerance test (OGTT), and increased 2-[(3)H]deoxy-d-glucose (2-[(3)H]DG) uptake into skeletal muscle with the increase in translocation of glucose transporter 4 (GLUT4) to the plasma membrane. Both blockers also decreased the in situ superoxide production in skeletal muscle. The decrease in plasma concentrations of glucose and insulin in the fed state and superoxide production in skeletal muscle, as well as GLUT4 translocation to the plasma membrane, after azelnidipine administration was not significantly affected by coadministration of an antioxidant, 2,2,6,6-tetramethyl-1-piperidinyloxy (tempol). However, those changes caused by olmesartan were further improved by tempol. Moreover, olmesartan enhanced the insulin-induced tyrosine phosphorylation of insulin receptor substrate-1 induced in skeletal muscle, whereas azelnidipine did not change it. Coadministration of azelnidipine and olmesartan further decreased the plasma concentrations of glucose and insulin, improved OGTT, and increased 2-[(3)H]DG uptake in skeletal muscle. These results suggest that azelnidipine improved glucose intolerance mainly through inhibition of oxidative stress and enhanced the inhibitory effects of olmesartan on glucose intolerance, as well as the clinical possibility that the combination of CCB and ARB could be more effective than monotherapy in the treatment of insulin resistance.

Topics: Angiotensin II Type 1 Receptor Blockers; Animals; Antimetabolites; Antioxidants; Azetidinecarboxylic Acid; Blood Glucose; Calcium Channel Blockers; Cyclic N-Oxides; Deoxyglucose; Diabetes Mellitus, Type 2; Dihydropyridines; Glucose Intolerance; Glucose Tolerance Test; Glucose Transporter Type 4; Imidazoles; Insulin; Insulin Receptor Substrate Proteins; Male; Mice; Mice, Inbred C57BL; Oxidative Stress; Phosphoproteins; Spin Labels; Superoxides; Tetrazoles