Regulatory Mechanism Of Ketamine On Intracellular Magnesiumions In Cardiomyocytes

Objective:The mechanism of ketamine in mediating increase of intracellular free magnesium ([Mg2+];) in myocardial cells were investigated in this study.Methods:Single myocardial cells were isolated from the rat. using ion fluorescence method to detect [Mg2+]i in myocardial intracellular dynamically. In the presence or absence of extracellular Na+and intracellular Ca+, the effect of ketamine on [Mg2+]i were observed respectively. Pretreat cardiac cells with P MAPK inhibitor20minute and observing whether the effect of ketamine on [Mg2+]i are blocked.Results:1.Fluorescence was measured that the basal [Mg2+]i of rat ventricular myocytes calculated with the intracellular curve averaged0.92mmol/L±0.06mmol/L,2. In the presence of extracellular Mg2+1mmol/L, the concentration of [Mg2+]i increase in ventricular myocytes induced by Ketamine at26.6%±5.8%. In the presence of extracellular Mg2+0mmol/L, the concentration rate of [Mg2+]i increase in ventricular myocytes induced by Ketamine at26.3%±7.6%. Statistical results showed that the difference between the two groups was not statistically significant (P>0.05).3. In the presence of extracellular Mg2+0mmol/L, the concentration of Ketamine at0、1、3、10、30、100、300、1000、3000和10000(μmol/L), increased [Mg2+]i in ventricular myocytes respectively at1.18%±1.38%.1.21%±1.36%.2.29%±1.8%.26.64%±4.04%.88.59%±30.52%.184.08%±41.47%.384.75%±53.57%.416.02%±50.46%.426.02%±53.32%. Ketamine increased [Mg2+]i in concentration-dependent manner with an EC50at266.61±34.89μmol/L4. In the presence of extracellular BAPTA-AM0mmol/L, the concentration of [Mg2+]i increased at26.71%±6.8%in ventricular myocytes induced by Ketamine. In the presence of extracellular Mg2+0mmol/L. the concentration of [Mg2+]i increased at24.35%±6.5%in ventricular myocytes induced by Ketamine. Statistical results showed that no differences were considered significant (P>0.05). The ketamine-induced increase of [Mg2+]i was not affected by intracellular Ca2+5. In the presence of extracellular Na+145mmol/L, the concentration of [Mg2+]i increased at26.6%±5.8%in ventricular myocytes induced by Ketamine. In the presence of extracellular Na+0mmol/L, the concentration of [Mg2+]i increased at26.3%±7.6%in ventricular myocytes induced by Ketamine. Statistical results showed that no differences were considered significant (P>0.05). Ketamine-induced increase of [Mg2+]i was not affected by extracellular Na+6. In the presence of extracellular Mg2+, group A were incubated for20min by ketamine and group B cells were incubated for20min with10μmol/L SB202190before perfusion of ketamine. The results showed ketamine induced the concentration of the intracellular free magnesium ion increasing was significantly in group A.Ketamine-induced increase of [Mg2+]i at69.89%±3.9%in group B. The result suggest that ketamine induced the concentration of the intracellular free magnesium ion increasing was significantly blocked by the MAPK inhibitor-SB202190. Statistical results showed differences were considered significant(P<0.01). Ketamine may regulate [Mg2+]i through P38MAPK activating pathway.Conclusion:1.[Mg2+]i of rat ventricular myocytes calculated with the intracellular curve averaged0.92mmol/L±0.06mmol/L on resting state.2. The ketamine-induced increase of [Mg2+]i in concentration-dependent manner with an EC50at266.61±34.89μmol/L3. The ketamine-induced increase of [Mg2+]i maybe originate from intracellular.4. The ketamine-induced increase of [Mg2+]i was not affected by intracellular Ca2+.5. ketamine-induced increase of [Mg2+]i was not affected by extracellular Na+6. Ketamine may regulate [Mg2+]i through P38MAPK activating pathway.