Oxytocin-stimulated insulin release in a clonal beta-cell line RINm5F: involvement of phospholipase C-dependent and -independent pathways.

B Lee, T H Chen, W H Hsu

Index: Zhongguo Yao Li Xue Bao 17(5) , 390-4, (1996)

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Abstract

To study the mechanisms underlying oxytocin (Oxy)-induced insulin release.In a clonal pancreatic beta-cell line, RINm5F cells.Oxy increased insulin release and [Ca2+]i in a concentration-dependent manner. Oxy-induced insulin release was not altered by pretreatment with pertussis toxin (PT). U-73122 (2-8 mumol.L-1), a phospholipase C (PLC) inhibitor, concentration-dependently inhibited Oxy-induced increases in [Ca2+]i with IC50 value of 2.8 +/- 0.2 mumol.L-1. In addition, U-73122 diminished the Oxy-induced increase in intracellular concentration of inositol 1, 4, 5-triphosphate (IP3). U-73122 at 8 mumol.L-1 totally abolished the Oxy-induced increases in [Ca2+]i and IP3; however it reduced the Oxy-induced increase in insulin release only by 36% and 63% in the monolayer and suspended cell preparations, respectively.Oxy increases insulin release through both PLC and non-PLC mediated signal transduction mechanisms.