GOLGI-APPARATUS IS INVOLVED IN INTRACELLULAR CA2-PK1 CELLS( REGULATION IN EPITHELIAL LLC)

Several lines of evidence suggest that the Golgi apparatus is involved in Ca2+ regulation in renal epithelial LLC-PK1 cells. Laser scanning confocal microscopy (LSCM) was employed to establish that a prominent perinuclear region is occupied mainly by the Golgi apparatus in this c ell line. LSCM measurements in individual cells with the ionized Ca2indicator calcium green revealed that stimulation of LLC-PK1 cells wit h arginine vasopressin (AVP) resulted in the elevation of ionized Ca2 levels. However, the vasopressin-induced rise in ionized Ca2+ was att enuated if the Golgi apparatus was disassembled by pretreating the cel ls with brefeldin A (BFA). Subcellular measurements of total Ca2+ with ion microscopy in cryogenically prepared cells indicated that 1) with in 1 min of AVP treatment significant quantities of sequestered Ca2+ w ere released from the perinuclear Golgi region and 2) the BFA treatmen t reduced the total Ca2+ stored in the Golgi region. These observation s indicate that the Golgi apparatus is sensitive to hormonal stimulati on and may play important roles in intracellular Ca2+ regulation in LL C-PK1 cells.