Effects of ultrasound combined with microbubbles on intracellular Ca 2+ homeostasis in carboplatin-treated microenvironment of A549 cell line / 中华超声影像学杂志

ABSTRACT

Objective To investigate the effects of ultrasound combined with microbubbles on intracellular Ca2+ homeostasis in carboplatin ( CBP )-treated A549 cell and its possible mechanisms of inhibiting A549 cell line activity . Methods According to whether SonoVue was used or not ,and the different dose of CBP ,the groups A-F were arranged as the ultrasound(US) group(group A) ,the ultrasound combined with microbubbles ( USMB) group( group B) ,the low dose CBP ( 100 μg/ml) + US group( group C) ,the low dose CBP+USMB group( group D) ,the high dose CBP ( 200 μg/ml)+ US group ( group E) and the high dose CBP+USMB group( group F) .A549 cells were bathed and washed by a calcium-free buffer , loaded with Ca2+ indicator fluo-4 AM . Real-time images were acquired using laser confocal microscopy .The fluorescence intensity of intracellular calcium ion concentration ([Ca2+ ]i) in individual living cell was observed and the calcium overload was analyzed . Results After ultrasound irradiation ,the normalized fluorescence intensity of [Ca2+ ]i increased rapidly ,then returned to a new homeostasis (selected cells in groups A ,B ,E ,F) or experienced a second calcium oscillation ( some cells in group C and D) . All the selected cells in group B and some cells in group C and D exhibited superimposed oscillations . The calcium overloading time in group D was longer than those of any other groups . Four cells in group A experienced delayed calcium oscillations . Compared with group A ,the selected cells in other groups exhibited a larger amplitude of calcium oscillation( all P < 0 .05) and the selected cells in group B and D exhibited calcium oscillation for a longer period of time( all P <0 .05) . Conclusions In the calcium-free buffer ,US ,USMB , CBP+ US ,CBP + USMB are direct stimuli of calcium overload in A 549 cells . SonoVue ,CBP ,CBP +SonoVue are all synergistic stimuli of calcium overload in A 549 cells irradiated by ultrasound .US ,USMB and CBP may synergistically induce calcium release from intracellular store sites in A 549 cells . Calcium overload is a possible mechanism of ultrasound combined with microbubbles in assisting CBP chemotherapy .