分类： 生物学 >> 生物物理学 提交时间： 2016-05-12
Wei, Ming-Yu
Xue, Lu
Tan, Li
Sai, Wen-Bo
Liu, Xiao-Cao
Jiang, Qiu-Ju
Shen, Jinhua
Peng, Yong-Bo
Zhao, Ping
Yu, Meng-Fei
Chen, Weiwei
Ma, Li-Qun
Liu, Qing-Hua
Wei, Ming-Yu
Xue, Lu
Tan, Li
Sai, Wen-Bo
Liu, Xiao-Cao
Jiang, Qiu-Ju
Shen, Jinhua
摘要： The participation of large-conductance Ca2+ activated K+ channels (BKs) in chloroquine (chloro)-induced relaxation of precontracted airway smooth muscle (ASM) is currently undefined. In this study we found that iberiotoxin (IbTx, a selective inhibitor of BKs) and chloro both completely blocked spontaneous transient outward currents (STOCs) in single mouse tracheal smooth muscle cells, which suggests that chloro might block BKs. We further found that chloro inhibited Ca2+ sparks and caffeine-induced global Ca2+ increases. Moreover, chloro can directly block single BK currents completely from the intracellular side and partially from the extracellular side. All these data indicate that the chloro-induced inhibition of STOCs is due to the blockade of chloro on both BKs and ryanodine receptors (RyRs). We also found that low concentrations of chloro resulted in additional contractions in tracheal rings that were precontracted by acetylcholine (ACH). Increases in chloro concentration reversed the contractile actions to relaxations. In the presence of IbTx or paxilline (pax), BK blockers, chloro-induced contractions were inhibited, although the high concentrations of chloro-induced relaxations were not affected. Taken together, our results indicate that chloro blocks BKs and RyRs, resulting in abolishment of STOCs and occurrence of contraction, the latter will counteract the relaxations induced by high concentrations of chloro.
分类： 生物学 >> 生物物理学 >> 生物物理、生物化学与分子生物学 提交时间： 2016-05-11
摘要： Calcium (Ca2+) oscillations play a central role in varieties of cellular processes including fertilization and immune response, but controversy over the regulation mechanisms still exists. It has been known that nitric oxide (NO) dependently regulates Ca2+ signaling in most physiopathological processes. Previous study indicated that eNOS translocation during some pathological process influences intracellular Ca2+ homeostasis. In this study, we investigated the role and mechanism of NO on Ca2+ release by overexpressing eNOS in cytoplasm (Cyto-eNOS) and endoplasmic reticulum (ER-eNOS) of HeLa cells. We found that the properties of Ca2+ release were altered by the overexpression of eNOS. The amplitude and frequency of extracellular ATP (eATP)-induced Ca2+ oscillation were enhanced in both Cyto-eNOS and ER-eNOS cells, respectively. Especially, the enhancement of the amplitude and frequency of the Ca2+ oscillation was much more significant in the ER-eNOS cells than that of Cyto-eNOS cells. Further study indicated that this effect was abrogated by NO inhibitor, 1..-NAME, suggesting it was not an artificial result induced by ER stress. Furthermore, an up-regulated phosphorylation of phospholamban (PLB) was observed and the sarco-endoplasmic reticulum Ca2tATPase (SERCA) function was activated followed by the significant increase in the ER Ca2+ load. Taken together, we revealed a novel regulatory mechanism of Ca2+ oscillation. (C) 2014 Elsevier Inc. All rights reserved.
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