KISEP Original Articles 12 3 2001 RINm5F 인슐린종세포에서막전압및이온전류들에미치는 Fluoxetine의효과 ABSTRACT 박기창 1* 오국택 1 차승규 2 이건일 2 박규상 2 정성우 2 공인덕 2 이중우 2 Effects of Fluoxetine on Membrane Potential and Ionic Currents in RINm5F Insulinoma Cells Ki Chang Park, MD, 1 Guk Taek Oh, MD, 1 Seung Kyu Cha, MS, 2 Keon Il Lee, MD, 2 Kyu Sang Park, MD, 2 Seong Woo Jeong, PhD, 2 In Deok Kong, MD 2 and Joong Woo Lee, PhD 2 1 Department of Psychiatry, 2 Physiology, Yonsei University Wonju College of Medicine, Wonju, Korea ObjectiveThe purpose of this study was to investigate the effects of fluoxetine Prozac on membrane potential and ionic currents in RINm5F insulinoma cells. MethodsMembrane potential and ionic currents in RINm5F cell were recorded by using whole-cell and perforated-patch clamp techniques. ResultsUnder current clamp conditions, diazoxide 200 M, an activator of K ATP channels, induced a hyperpolarization of the resting membrane potential 16.11.4 mv, n8, which was accompanied by a abolition of action potential firing. This diazoxide-induced hyperpolarization was blocked by glibenclamide 10 M. Fluoxetine produced significant depolarization of membrane potential 15.93.1 mv, n5 and blocked diazoxide-induced hyperpolarization. Diazoxide activated inward currents in the presence of high external K 90 mmat a holding potential of 60 mv. Fluoxetine suppressed diazoxide-activated currents in a concentration-dependent IC 50 0.84 M manner. However, the inhibitory action of fluoxetine was not specific to K ATP currents because it also inhibited both voltage-activated K and Ca 2 currents in a concentration-dependent manner. K ATP currents were more sensitive to fluoxetine block than both voltage-activated K and Ca 2 currents. ConclusionOur results indicate that fluoxetine increased excitability of RINm5F cells mainly by the preferential block of K ATP currents. Fluoxetine-induced depolarization may influence insulin secretion in insulinoma cells. Korean J Psychopharmacol 2001;123:233-241 KEY WORDSFluoxetine K ATP channel Membrane potential Ionic current Insulin secretion. 서 론 233
234 1. 세포배양 실험재료및방법 2. 전기생리적실험 Korean J Psychopharmacol 2001;123:233-241
3. 세포외및전극내용액 4. 약물 5. 자료분석 235
결과 1. RINm5F 세포에서안정막전압에대한 ATP-민감성 K + 통로효현제및차단제의효과 2. Fluoxetine이안정막전압및 diazoxide에의해유발된과분극에미치는효과 3. RINm5F 세포에서 K ATP 전류의특성 Figure 1. Effects of fluoxetine on membrane potential of RINm5F cell. AUnder current-clamp mode, application of diazoxide a KATP opener, 200 M induced hyperpolarization and inhibited slow waves and spikes. Glibenclamide a KATP blocker, 10 M blocked diazoxide-induced hyperpolarization and restored spontaneous spikes. B Fluoxetine 10 M induced significant depolarization, and decreased slow waves and action potentials. CFluoxetine also blocked diazoxide-induced hyperpolarization. 236 Korean J Psychopharmacol 2001;123:233-241
4. Fluoxetine이막전압의존적 K + 통로에미치는영향 Figure 2. Effects of fluoxetine on inward KATP currents in RINm5F cell. AChanging the external solution from 5 mm K to 90 mm K elicited an inward current. Addition of diazoxide 200 M activated a steady-state current that was blocked largely by glibenclamide 10 M. BThe diazoxide-activated current was blocked by fluoxetine in concentation-dependent manners. Figure 3. Effects of fluoxetine on voltage-activated K currents. AWhole-cell outward currents K elicited by 200 ms test-pulses to potentials between 80 mv and 70 mv in steps 10 mv under control condition uppermost and after the addition of 10 M fluoxetine lowermost. BCurrent-voltage relationships were measured at the peak of the currents in the absence and presence of fluoxetine. CTime course of fluoxetine effect was shown. 237
5. Fluoxetine이막전압의존적 Ca 2+ 전류에미치는효과 Figure 4. Effects of fluoxetine on Ca 2 currents. Ba 2 was used a charge carrier to record Ca 2 currents. ACa 2 current records elicited from a holding potential of 80 mv by 200 ms depolarizing steps to the indicated test potentials under control condition uppermost, and after the addition of 10 M fluoxetine lowermost. BCurrent-voltage relationship in the absence and presence of 10 M fluoxetine. Peak Ca 2 currents were plotted at the test potential as a normalized value. C Time course of fluoxetine effect was shown. Figure 5. Effects of fluoxetine on KATP and both voltage-activated K and Ca 2 current. AConcentration dependency of the inhibition of the KATP and both voltage-activated K and Ca 2 current by fluoxetine. IC50 concentration for fluoxetine was 0.87 M, 4.03 M, and 4.26 M, respectively. BPercent inhibition of KATP, K Kv and Ca 2 currents compared at a concentration of 1 M fluoxetine, that is therapeutic concentration of fluoxetine. Each bar represents the means.e. **p0.001. 238 Korean J Psychopharmacol 2001;123:233-241
6. 혈중농도하에서 fluoxetine이이온통로에미치는영향비교 고 찰 239
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