Activation?of?calcium-sensing?receptors?is?associated?with?apoptosis?in?a?model?of?simulated?cardiomyocytes?ischemia/reperfusion

Objective:?Calcium-sensing?receptors?(CaSRs)?are?G-protein?coupled?receptors?which?maintain?systemic?calcium?homeostasis?and?participate?in?hormone?secretion,?activation?of?ion?channels,?cell?apoptosis,?prolifera-tion,?and?differentiation.?Previous?studies?have?shown?that?CaSRs?induce?apoptosis?in?isolated?adult?rat?heart?and?in?normal?neonatal?rat?cardiomyocytes?by?G-protein-PLC-IP3?signaling?transduction.?However,?little?knowledge?is?presently?available?concerning?the?role?of?CaSRs?in?the?apoptosis?induced?by?ischemia?and?reperfusion?in?neo-natal?cardiomyocytes.?Methods:?Primary?neonatal?rat?ventricular?cardiomyocytes?were?incubated?in?ischemia-mimetic?solution?for?2?h,?and?then?re-incubated?in?normal?culture?medium?for?24?h?to?establish?a?model?of?simu-lated?ischemia/reperfusion?(I/R).?Cardiomyocyte?apoptosis?was?detected?by?terminal?deoxynucleotidyl?transferase-mediated?dUTP?nick?end?labeling?(TUNEL).?The?expression?of?CaSRs?mRNA?was?detected?by?real-time?reverse?transcription?polymerase?chain?reaction?(RT-PCR).?In?addition,?the?expressions?of?caspase-3?and?Bcl-2?were?ana-lyzed?by?western?blot.?Results:?The?simulated?I/R?enhanced?the?expression?of?CaSRs?and?cardiomyocyte?apopto-sis.?GdCl3,?a?specific?activator?of?CaSRs,?further?increased?the?expression?of?CaSRs?and?cardiomyocyte?apoptosis,?along?with?up-regulation?of?caspase-3?and?down-regulation?of?Bcl-2.?Conclusion:?CaSRs?are?associated?with?I/R?injury?and?apoptosis?in?neonatal?rat?ventricular?cardiomyocytes?via?suppressing?Bcl-2?and?promoting?caspase-3?expression.