This Article Full Text Full Text (PDF) Purchase Article View Shopping Cart Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Copyright Permission Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Chik, C. L. Articles by Ho, A. K. Search for Related Content PubMed PubMed Citation Articles by Chik, C. L. Articles by Ho, A. K.

Insulin and Insulin-Like Growth Factor-I Inhibit the L-Type Calcium Channel Current in Rat Pinealocytes¹

Department of Medicine (C.L.C.) and Department of Physiology (B.L., E.K., A.K.H.), University of Alberta, Edmonton, Alberta, Canada

Address all correspondence and requests for reprints to: C.L. Chik, Room 733 MSB, University of Alberta, Edmonton, Alberta T6G 2H7, Canada.

Tyrosine phosphorylation has recently been shown to modulate ion channel activity. In the present study, the effect of growth factors on the L-type Ca²⁺ channel current in rat pinealocytes was investigated using the whole cell version of the patch clamp technique. Both insulin and insulin-like growth factor-I (IGF-I) inhibited the L-type Ca²⁺ channel current. This inhibition was dependent on concentration, with median effective concentration (EC₅₀) values of 60 nM for insulin and 0.14 nM for IGF-I. Heat-inactivated insulin or IGF-I had no effect on the L-type Ca²⁺ channel current. The presence of anti-IGF-I receptor antibodies blocked the inhibitory effect of IGF-I on the L-type Ca²⁺ channel current. Two other growth factors, nerve growth factor and epidermal growth factor, had no effect on this current. The effects of insulin and IGF-I were blocked by lavendustin A, a tyrosine kinase inhibitor. Calphostin C, a protein kinase C inhibitor, attenuated the effect of insulin and IGF-I, whereas wortmannin, a phosphatidylinositol 3-kinase inhibitor, was ineffective. These observations indicate that insulin and IGF-I inhibit the L-type Ca²⁺ channel current in rat pinealocytes, and that tyrosine phosphorylation is involved in these effects of insulin and IGF-I.

This article has been cited by other articles:

				J. Vela, M. I. Perez-Millan, D. Becu-Villalobos, and G. Diaz-Torga Different kinases regulate activation of voltage-dependent calcium channels by depolarization in GH3 cells Am J Physiol Cell Physiol, September 1, 2007; 293(3): C951 - C959. [Abstract] [Full Text] [PDF]

				C. Ibarra, M. Estrada, L. Carrasco, M. Chiong, J. L. Liberona, C. Cardenas, G. Diaz-Araya, E. Jaimovich, and S. Lavandero Insulin-like Growth Factor-1 Induces an Inositol 1,4,5-Trisphosphate-dependent Increase in Nuclear and Cytosolic Calcium in Cultured Rat Cardiac Myocytes J. Biol. Chem., February 27, 2004; 279(9): 7554 - 7565. [Abstract] [Full Text] [PDF]

				M. J. Davis, X. Wu, T. R. Nurkiewicz, J. Kawasaki, P. Gui, M. A. Hill, and E. Wilson Regulation of ion channels by protein tyrosine phosphorylation Am J Physiol Heart Circ Physiol, November 1, 2001; 281(5): H1835 - H1862. [Abstract] [Full Text] [PDF]

				C. Sims, J. Chiu, and R. D. Harvey Tyrosine Phosphatase Inhibitors Selectively Antagonize beta -Adrenergic Receptor-Dependent Regulation of Cardiac Ion Channels Mol. Pharmacol., April 13, 2001; 58(6): 1213 - 1221. [Abstract] [Full Text]

				C. L. Chik, B. Li, T. Negishi, E. Karpinski, and A. K. Ho Ceramide Inhibits L-Type Calcium Channel Currents in Rat Pinealocytes Endocrinology, December 1, 1999; 140(12): 5682 - 5690. [Abstract] [Full Text]