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Horm Metab Res 2003; 35(7): 402-406
DOI: 10.1055/s-2003-41620
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© Georg Thieme Verlag Stuttgart · New York

Effects of Some Vanadyl Coordination Compounds on the In Vitro Insulin Release from Rat Pancreatic Islets

M.  T.  Conconi 1 , E.  De Carlo 2 , S.  Vigolo 1 , C.  Grandi 1 , G.  Bandoli 1 , N.  Sicolo 2 , G.  Tamagno 2 , P.  P.  Parnigotto 1 , G.  G.  Nussdorfer 3
  • 1Departments of Pharmaceutical Sciences, University of Padua, Padua, Italy
  • 2Departments of Medical and Surgical Sciences, University of Padua, Padua, Italy
  • 3Departments of Human Anatomy and Physiology, University of Padua, Padua, Italy
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Publication History

Received 24 October 2002

Accepted after Revision 8 January 2003

Publication Date:
21 August 2003 (online)

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Abstract

Many lines of evidence indicate that vanadium inorganic salts possess insulin-mimetic and insulinotropic properties. However, they are poorly absorbed, so high oral doses are required to achieve effective plasma concentrations with possible undesirable toxic side-effects ensuing. Various organically-chelated vanadium compounds have been synthesized that are more potent than inorganic vanadium salts in their insulin-like effects due to their greater bioavailability. Unfortunately, little is known about the possible insulin secretagogue action of organic vanadyl coordination compounds. Hence, we investigated the effect of [VO(metformin)2]·H2O, [VO(salicylidene-ethylenedimmine)2] and [VO(pyrrolidine-N-dithiocarbamate)2](VODTC) on insulin release from isolated rat pancreatic islets, and compared it to that of vanadyl sulfate (VOSO4). Of the three coordination compounds, only VODTC was found to exert insulin secretagogue action. VODTC, within concentrations ranging from 0.1 to 1.0 mM, enhanced both basal and glucose (11 mM)-stimulated insulin release. The effect involves calcium channels, since it was not appreciable in Ca2+-free medium. The stimulating action of VODTC required the presence of the whole metal-chelator complex inasmuch as the chelator DTC alone was ineffective. VOSO4 was unable to bring about any significant rise in insulin release from isolated islets. Taken together, our findings indicate that VODTC may be considered a potential elective pharmaceutical tool in the therapy of diabetes, especially of type 2, through its concomitant stimulatory effect on insulin secretion and insulin-mimetic action.

Key words

Vanadium - Vanadyl coordination compounds - Pancreatic islets - Insulin - Rat