Effects of verapamil and elgodipine on isoprenaline-induced metabolic responses in rabbits

Verapamil (0.17 mug kg(-1) min(-1) intravenous, i.v.) but not elgodipine (3 5 ng kg(-1) min(-1)) modestly enhanced the weak blood glucose increase indu ced by the i.v. infusion of isoprenaline (0.3 mug kg(-1) min(-1)) in consci ous rabbits. However, elgodipine but nor verapamil suppressed the increase in circulating insulin evoked by the agonist. Both drugs enhanced the rise in plasma lactate mediated by isoprenaline but only elgodipine potentiated the lipolytic effect of the agonist. in isolated islets elgodipine (10(-6) M) blocked forskolin (10(-6) M)-induced insulin release. However, in rabbit adipocytes elgodipine potentiated both glycerol release and cAMP accumulat ion induced by isoprenaline (10(-8)-10(-6) M). Excess K+ (40-60 mM) did not alter basal lipolysis or the response to isoprenaline in either rabbit or mouse adipocytes. Therefore, Ca2+ influx through L-type Ca2+ channels does not seem to play a significant role in the lipolytic effect of isoprenaline . Metabolic alterations found with Ca2+ channel antagonists were of minor i ntensity and probably devoid of pathological implications. (C) 2001 Elsevie r Science B.V. All rights reserved.