Stimulatory release of lipoprotein lipase activity from rat fat pads by vanadate.
Vanadate stimulated the release of lipoprotein lipase (LPL) activity from rat fat pads into the medium in a time- and dose-dependent manner. It exerted the synergetic effect with heparin. The stimulatory effects of vanadate and heparin were decreased by incubation in Na+- or Ca2+-free media but were well preserved in K+-free medium. Amiloride inhibited the vanadate-stimulated release of LPL activity in a dose-dependent manner, but did not inhibit the heparin-stimulated release of LPL activity. Colchicine, antimycin A, and carbonyl cyanide m-chlorophenylhydrazone suppressed the stimulatory effect of vanadate, but cycloheximide did not. Preincubation of the fat pads with the tetrakis (acetoxymethyl) ester of quin 2 (quin 2-AM) inhibited the vanadate-stimulatory release of LPL activity without affecting basal activity. The concentration required for half-maximal inhibition of the action of vanadate by quin 2-AM was calculated to be 39 microM, suggesting that the action of vandate was dependent on intracellular Ca2+ concentration. The heparin-stimulated release, on the other hand, was not inhibited even at higher concentrations of quin 2-AM (up to 200 microM). These findings suggest that vanadate stimulates the release of LPL activity through mechanisms of action involving amiloride-sensitive and calcium-dependent pathways with a requirement of metabolic energy.
Ueki
H
H
Department of Biochemistry, Faculty of Pharmacy and Pharmaceutical Sciences, Fukuyama University, Hiroshima, Japan.
Sera
M
M
Tanaka
K
K
D000273:Adipose Tissue / Q000187:drug effects / Q000378:metabolism*; D000584:Amiloride / Q000494:pharmacology; D000634:Aminoquinolines; D000818:Animals; D000968:Antimycin A / Q000494:pharmacology; D002118:Calcium / Q000494:pharmacology; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone / Q000494:pharmacology; D002614:Chelating Agents / Q000494:pharmacology; D003078:Colchicine / Q000494:pharmacology; D003513:Cycloheximide / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D006493:Heparin / Q000494:pharmacology; D007700:Kinetics; D008071:Lipoprotein Lipase / Q000378:metabolism*; D008297:Male; D011188:Potassium / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D012964:Sodium / Q000494:pharmacology; D014638:Vanadates / Q000008:administration & dosage / Q000494:pharmacology*
D000634:Aminoquinolines; D002614:Chelating Agents; D014638:Vanadates; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone; D000968:Antimycin A; D000584:Amiloride; C035738:Quin2-acetoxymethyl ester; D006493:Heparin; D003513:Cycloheximide; D012964:Sodium; D008071:Lipoprotein Lipase; D011188:Potassium; D003078:Colchicine; D002118:Calcium