• 대한수의학회지
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• 제36권2호
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• pp.305-312
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• 1996

Cell volume regulatory mechanisms are usually disclosed by exposure of cell to anisotonic media. If a cell is suddenly exposed to hypotonic media, it swells initially like an osmometer but within minutes regains its original cell volume. This behavior has been labelled as regulatory cell volume decrease(RVD). RVD is believed to result from the loss of permeable ions through the membrane. In this study, we examined hypotonically induced changes in the membrance currents involved in RVD by using whole cell voltage clamp technique in the unfertilized hamster egg. At -40mV of the holding potential, the stationary current was maintained in the hamster egg exposed to isotonic solution composed of, mainly, 115mM NaCl and 40mM mannitol. Hypotonic solution was prepared by removing mannitol. Therefore, the concentrations of $Na^+$ and $Cl^-$ in this hypotonic media were the same as those in the isotonic solution. Following 30 to 60 sec after applying the hypotonic media to the egg, the inward current was evoked. This inward current was eliminated by $100{\mu}M$ 4-acetamido-4'-isothiocyanostil-bene-2,2'-disulfonic acid(SITS), an anion channel blocker, leaving the small outward current component. Further addition of 2mM $Ba^{2+}$, a broad $K^+$ channel blocker, completely abolished the small outward current left even in the presence of SITS during hypotonic stress. These results suggest that $K^+$ and $Cl^-$ move out of cells, resulting in RVD. To test the involvement of $Na^+$ in RVD, 20mM Na-isethionate was substituted for mannitol in isotonic media(135mM $Na^+$) and Na-isethionate (20mM) was freed the hypotonic solution. Only $Cl^-$ concentration in both isotonic and hypotonic media was kept constant at 115mM, whereas concentration of $Na^+$ was lowered in hypotonic solution to 115mM from 135mM in isotonic solution. Hypotonic medium induced the outward current in the egg equilibrated isotonically. This current was reduced by $100{\mu}M$ SITS but was augmented by 2 mM $Ba^{2+}$. In terms of RVD, these results imply that $Cl^-$ efflux is coupled with $K^+$, maybe for electroneutrality during hypotonic stress and/or with $Na^+$ via unknown transport mechanism(s). From the overall results, the hypotonic stress facilitates the movement of $Cl^-$ and $K^+$ out of the hamster egg to regain cellular volume with electroneutrality. If there exist a difference in $[Na^+]_0$ between isotonic and hypotonic solution, another transport mechanism concerned with $Na^+$ may, at least partly, participate in regulatory volume decrease.

• 대한의생명과학회지
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• 제29권4호
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• pp.280-286
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• 2023

In humic substances, fulvic acid (FA) is a subclass of diverse compounds known as humic substances, which are by-products of organic degradation from microorganisms. FA can suppress the proliferation of tumor cells. Despite numerous studies, the exact mechanism for the various effects of FA is not clearly understood. Based on results demonstrating anti-proliferation effects on human cancer, we investigated whether FA has similar effects on lung cancer in this study. Firstly, the anti-cancer effect of FA in pulmonary epithelial tumor cell lines (TC-1 cells) was examined by confirming its inhibitory effect on the cell proliferation of TC-1 cells. TC-1 cell proliferation was reduced by FA on a dose-dependent and time-dependent manner. After 24 hours of FA treatment, cell morphological changes such as cell volume decrease, non-adherence and increased number of apoptotic cells were clearly observed. In addition, FA induced a DNA ladder pattern by increased of DNA fragments in TC-1 cells. In the intracellular regulatory pathway by FA, we confirmed that FA induced the reduction of the anti-apoptotic protein, Bcl-2 protein levels. These results indicate that FA has anticancer effect by inducing intracellular apoptotic pathway. Further research on the mechanism of anticancer effects will be basic data for the development of potential anticancer drugs.

• Biomolecules & Therapeutics
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• 제23권3호
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• pp.225-232
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• 2015

We identified a novel Akt signaling mechanism that mediates fucoidan-induced suppression of human colon cancer cell (HT29) proliferation and anticancer effects. Fucoidan treatment significantly inhibited growth, induced G1-phase-associated upregulation of p21WAF1 expression, and suppressed cyclin and cyclin-dependent kinase expression in HT29 colon cancer cells. Additionally, fucoidan treatment activated the Akt signaling pathway, which was inhibited by treatment with an Akt inhibitor. The inhibition of Akt activation reversed the fucoidan-induced decrease in cell proliferation, the induction of G1-phase-associated p21WAF1 expression, and the reduction in cell cycle regulatory protein expression. Intraperitoneal injection of fucoidan reduced tumor volume; this enhanced antitumor efficacy was associated with induction of apoptosis and decreased angiogenesis. These data suggest that the activation of Akt signaling is involved in the growth inhibition of colon cancer cells treated with fucoidan. Thus, fucoidan may serve as a potential therapeutic agent for colon cancer.

• 한국생물물리학회:학술대회논문집
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• 한국생물물리학회 2001년도 학술 발표회 진행표 및 논문초록
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• pp.57-57
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• 2001

Intracellular pH(pH$\sub$i/) is strictly regulated since it is related to various cellular events such as contractility, signal transduction, ion regulation, cell volume, and energy production etc. In physiological conditions, pH$\sub$i/ of arteriolar smooth muscle faced substantial pressure to be changed during the regulation of blood flow. Therefore it is very important to know the regulatory mechanism of pH$\sub$i/.(omitted)