Effect of nifedipine and verapamil on carbohydrate metabolism in hypertensive patients with impaired glucose tolerance.
Intracellular Ca2+ influx is an essential step in insulin (I) release. Calcium antagonists are reported to reduce I release in vitro and in patients with impaired glucose tolerance (IGT) during acute administration. Their effects during long-term therapy are still controversial. To evaluate the effects of chronic verapamil (V) and nifedipine (N) on carbohydrate metabolism, 12 hypertensive patients (WHO II; aged 37-64 years) with IGT underwent intravenous glucose tolerance tests (IVGTT) (0.33 g/kg body weight in 3 min), arginine (A) infusion (30 g/30 min), and hypoglycemic stress (regular insulin 0.15 U/kg body weight) during which blood levels of glucose (G), I, growth hormone (GH), glucagon (IRG), and cortisol (C) were measured. The patients were then randomized to V (120 mg b.i.d.) or N (20 mg b.i.d.) treatment and, 1 month later, both IVGTT and A infusion were repeated. Hormone determinations were performed by the radioimmunoassay (RIA) and G by the enzymatic method. The patients were maintained on their usual diet for the duration of the study. The rate of decline of G during IVGTT was expressed as Conard's K coefficient (K; normal values greater than 1.3). I and GH during IVGTT were evaluated as the differences between basal and peak values. I, IRG, and GH during A infusion were analyzed as incremental areas. Our results show that neither V nor N impaired carbohydrate metabolism in hypertensive patients with IGT.
Dessì-Fulgheri
P
P
Cattedra di Patologia Medica II, Sassari University, Italy.
Pacifico
A
A
Bandiera
F
F
Rubattu
S
S
Madeddu
P
P
Glorioso
N
N
Maioli
M
M
Delitala
G
G
Tomasi
P
P
Rappelli
A
A
D000328:Adult; D001120:Arginine / Q000008:administration & dosage; D001786:Blood Glucose / Q000032:analysis; D050260:Carbohydrate Metabolism; D005951:Glucose Tolerance Test; D013006:Growth Hormone / Q000097:blood; D006801:Humans; D006973:Hypertension / Q000188:drug therapy* / Q000503:physiopathology; D007003:Hypoglycemia / Q000503:physiopathology; D007262:Infusions, Intravenous; D008875:Middle Aged; D009543:Nifedipine / Q000627:therapeutic use*; D010187:Pancreatic Hormones / Q000097:blood; D011897:Random Allocation; D014700:Verapamil / Q000627:therapeutic use*
D001786:Blood Glucose; D010187:Pancreatic Hormones; D013006:Growth Hormone; D001120:Arginine; D014700:Verapamil; D009543:Nifedipine