IMPROVEMENT OF INSULIN SENSITIVITY FOR GLUCOSE-METABOLISM WITH THE LONG-ACTING CA-CHANNEL BLOCKER AMLODIPINE IN ESSENTIAL HYPERTENSIVE SUBJECTS

To clarify whether the long-acting calcium-channel blocker amlodipine restores insulin insensitivity in essential hypertension, insulin sens itivity tests were performed at the physiological steady-state insulin level (45 to 55 mu U/mL) before and after amlodipine (2.5 to 7.5 mg/d ) administration for 2 to 4 months in borderline and mild essential hy pertensive subjects. Instead of somatostatin, Sandostatin (Sandoz, Bas el, Switzerland) was used for the determination of steady state plasma glucose (SSPG) in the same way as previously described. SSPG, which w as initially high (212.9 +/- 18.0 mg/dL, mean +/- SE), was significant ly reduced to 169.8 +/- 14.7 after amlodipine treatment. Responses of ketone bodies during the test at 30 minutes, which reflect the insulin effect on lipolysis in adipose tissue and hepatic fatty acid oxidatio n, also improved after amlodipine treatment. Norepinephrine, noted to be mildly elevated after amlodipine treatment, decreased during the se nsitivity test at 2 hours probably due to the sedative effect, without any change in the fractional extraction of Na. This indicates that th e physiological level of insulin does not activate sympathetic nerve a ctivity or stimulate Na reabsorption. The long-acting calcium-channel blocker amlodipine has significantly improved the initially decreased insulin sensitivity for glucose metabolism at least partially in borde rline or mild essential hypertension. Copyright (C) 1995 by W.B. Saund ers Company