- 期刊
Functional Coupling of Voltage-Depengent L-Type Ca(superscript 2+) Current to Ca(superscript 2+)-Activated K(superscript +) Current in Pituitary GH3 Cells
並列摘要
Ca(superscript 2+)-activated K(superscript +) currents (I(subscript K(ca))) can contribute to action potential repolarization and after-hyperpolarization in GH3 cells. In this study, we examined how the activation of I(subscript K(Ca)) at the cellular level could be functionally coupled to Ca(superscript 2+) influx through L-type Ca(superscript 2+) channels. A 30-msec Ca(superscript 2+) influx step to 0 mV was found to exhibit substantial contribution of Ca(superscript 2+) influx through the activation of I(subscript (Ca,L)) to the activation of I(subscript K(Ca)). A bell-shaped relationship between the conditioning potentials and the integrated I(subscript K(Ca)) was observed, suggesting that the magnitude of integrated I(subscript Ca,L) correlates well with that of integrated I(subscript K(Ca)) in the same cell. A linear relationship of integrated I(subscript Ca,L) and integrated I(subscript K(Ca)) was found with a coupling ratio of 69±7. The value of the coupling ratio was unaffected by the presence of Bay K 8644 or nimodipine, although these compounds could effectively affect the amplitudes of both I(subscript K(Ca)) and I(subscript Ca, L). However, tetrandrine could decrease the coupling ratio. Paxilline or intracellular Ca(superscript2+) buffer with EGTA decreased the coupling ratio, while apamin had no effect on it. Interestingly, phorbol 12-myristate 13-acetate also reduced the coupling ratio significantly, whereas thapsigargin increased this value. Thus, the present study indicates that the activation of I(subscript K(Ca)) during brief Ca(superscript 2+) influx, which is inhibited by paxilline, is coupled to Ca(superscript 2+) influx primarily through the L-type channels. The selective modulation of I(subscript K(Ca)) by second messengers or Ca(superscript 2+) release from internal stores may affect the coupling efficiency and hence cellular excitability.
延伸閱讀
- 張宜臻（2014）。1, 25(OH)2D3 against the toxicity of Aβ through increasing the protein expression of Glial cell line derived neurotrophic factor and following by activating Phosphatidylinositol 3 kinase / protein kinase B, decreasing cell apoptosis and tau protein hyperphosphorylation.〔碩士論文，臺北醫學大學〕。華藝線上圖書館。https://www.airitilibrary.com/Article/Detail?DocID=U0007-2407201415290600
- Chang, J. S. (2015). Roles of grouper heat shock cognate protein 70 and voltage-dependent anion selective channel protein 2 in NNV infection in vitro [doctoral dissertation, National Taiwan University]. Airiti Library. https://doi.org/10.6342/NTU.2015.00542
- 林建誠（2007）。To study the cellular function of a novel tumor suppressor gene SLR417:I. To search the interaction proteins of SLR417 by yeast two-hybrid System〔碩士論文，國立暨南國際大學〕。華藝線上圖書館。https://doi.org/10.6837/NCNU.2007.00105
- 孫德萍（1997）。(1)The Utilization of Cation Exchanger to Purify Sperm Motility Inhibitor (SMI) from Porcine Seminal Plasma; (2) The Anitumor Acitivy and Machanistic Study of Vitamin K3 against Human Cervical Carcino〔碩士論文，臺北醫學大學〕。華藝線上圖書館。https://www.airitilibrary.com/Article/Detail?DocID=U0007-1704200714264630
- Jan, C. R., Lu, Y. C., Jiann, B. P., Chang, H. T., Su, W., Chen, W. C., & Huang, J. K. (2002). Novel Effect of CP55,940, a CB1/CB2 Cannabinoid Receptor Agonist, on Intracellular Free Ca(superscript 2+) Levels in Bladder Cancer Cells. The Chinese Journal of Physiology, 45(1), 33-39. https://www.airitilibrary.com/Article/Detail?DocID=03044920-200203-45-1-33-39-a