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Investigation of the role of KATP channels in the cytotoxic effect of cypermethrin on rat-derived aortic smooth muscle cells

Söğüt, Fatma | Kibar, Deniz | Çömelekoğlu, Ülkü

We investigate role of atP sensitive potassium (KatP) channel in cytotoxic effect of cypermethrin on rataortic smooth muscle cells. cytotoxicity analysis was performed at 0, 0.1, 0.5, 10, 50, and 100 µMconcentrations of cypermethrin and the cell index (ci) was calculated. KatP currents were recorded usingpatch clamp technique for 50 and 100 µM concentrations and channel conductivity was determined byobtaining current-voltage characteristics. No cytotoxic effect was observed in the first 72 hours. at the96th hour, only at 100 µM concentration, the ci value decreased significantly compared to control groupand at 120 and 144th hours, it was observed that the ci value decreased significantly at all concentrations.currents and conductivities were significantly decreased at 50 and 100 µM concentrations. Results gaveclues that cypermethrin causes a cytotoxic effect on vascular smooth muscles and that KatP channelsmay have a role in the emergence of this effect.

Cytotoxic effect of silica nanoparticles on human retinal pigment epithelial cells

Çömelekoğlu, Ülkü | Kibar, Deniz | Yıldırımcan, Saadet | Yılmaz, Şakir Necat

In recent years, the use of nanotechnology-based methods has become widespread in the treatment of ocular diseases. Silica nanoparticles (SiO2 NPs) are most common used NPs in medical field due to their physicochemical properties. SiO2 NPs can easily cross biological membranes and interact with basic biological structures, causing structural and functional changes in cells. In this study, it was aimed to investigate the dose dependent effect of SiO2 NPs on retinal pigment epithelium (RPE) in vitro using electrobiophysical, biochemical and histological methods. A commercially purchased human RPE (hARPE-19) cell line was used in this study. Cells were divided into four groups as control, 50 mg/mL SiO2, 100 mg/mL SiO2 and 150 mg/mL SiO2 groups. Cell index, apoptotic activity, cell cycle and oxidative stress markers were measured in all groups. Findings in the present study showed that SiO2 nanoparticles reduced cell proliferation, increased oxidative stress, apoptosis and arrest in the G0/G1 phase of the cell cycle as dose dependent manner in ARPE-19 cells. In conclusion, SiO2 exposure can induce cytotoxic effects in RPE cell line. The results of this study provide clues that exposure to SiO2 nanoparticles may impair visual function and reduce quality of life. However, further stud...

Determination of the effect of silica nanoparticles on TRP currents in retinal pigment epithelial cells by entropy measurement

Söğüt, Fatma | Kibar, Deniz | Yılmaz, Şakir Necat | Çömelekoğlu, Ülkü

Ion channels in cell membranes are gated, water-filled pores that allow passive transport of ions across the membrane along their electrochemical gradient. Recent studies have shown that nanoparticles can interact with ion channels and change their currents kinetics properties of the channel. In this study, we used the transient receptor potential (TRP) channel currents in retinal pigment epithelial (RPE) cells recorded by whole-cell patch clamp technique to observe the silica nanoparticle-ion channel interaction. For whole cell recordings, we clamped membrane potential to −40 mV and used a ramp of 1000 ms duration for stimulation. The ramp was increased from −140 mV to +60 mV. We used windowed scalogram entropy and compared the results with windowed scale index method. Our results indicated that the temporal change of entropy using windowed scalogram entropy method is sensitive to demonstrating the effect of silica nanoparticles on RPE cell TRP currents. Furthermore, windowed scale index can analyze the temporal fluctuations in the aperiodicity of cell membrane current signals. Our findings suggest that entropy measurement methods may be useful in the function analysis of cell ion channels.

Ameliorative effects of paricalcitol against 1800-MHz mobile phone radiation-induced skin damage in rats

Aktaş, Savaş | Çömelekoğlu, Ülkü | Demirbağ, Burcu | Kibar, Deniz | Söğüt, Fatma | Yalın, Serap

This study aimed to evaluate the protective role of paricalcitol, a vitamin D analog, against hazardous effects of 1800-MHz radiofrequency (RF) radiation on the skin of male Wistar albino rats exposed one h/day for 4 weeks. The maximum specific absorption rate was calculated as 0.0042 W/kg. Superoxide dismutase and catalase activity, collagen bundle thickness, breaking force, energy, and stress were decreased, while malondialdehyde level and mast cell number were increased. The exposure to 1800-MHz RF radiation caused a reduction in skin biomechanical quality through oxidative stress and mast cell activation. The administration of paricalcitol caused a significant improvement.

N -Acetylcysteine-induced vasodilatation is modulated by K ATP channels, Na /K -ATPase activity and intracellular calcium concentration: An in vitro study

Çömelekoğlu, Ülkü | Sucu, Nehir | Yalın, Ali Erdinç | Yılmaz, Şakir Necat | Yalın, Serap | Söğüt, Fatma | Kibar, Kezban | Akkapulu, Merih

Background In this study, we aimed to investigate the role of ATP-sensitive potassium (KATP) channel, Na+/K+-ATPase activity, and intracellular calcium levels on the vasodilatory effect of N-acetylcysteine (NAC) in thoracic aorta by using electrophysiological and molecular techniques. Methods Rat thoracic aorta ring preparations and cultured thoracic aorta cells were divided into four groups as control, 2 mM NAC, 5 mM NAC, and 10 mM NAC. Thoracic aorta rings were isolated from rats for measurements of relaxation responses and Na+/K+-ATPase activity. In the cultured thoracic aorta cells, we measured the currents of KATP channel, the concentration of intracellular calcium and mRNA expression level of KATP channel subunits (KCNJ8, KCNJ11, ABCC8 and ABCC9). Results The relaxation rate significantly increased in all NAC groups compared to control. Similarly, Na+/K+- ATPase activity also significantly decreased in NAC groups. Outward KATP channel current significantly increased in all NAC groups compared to the control group. Intracellular calcium concentration decreased significantly in all groups with compared control. mRNA expression level of ABCC8 subunit significantly increased in all NAC groups compared to the control group. Pearson correlation analysis showed that relaxatio...