Abstract
To determine whether K(ATP) channels control liver growth, we used primary rat hepatocytes and several human cancer cell lines for assays. K(ATP) channel openers (minoxidil, cromakalim, and pinacidil) increased cellular DNA synthesis, whereas K(ATP) channel blockers (quinidine and glibenclamide) attenuated DNA synthesis. The channel inhibitor glibenclamide decreased the clonogenicity of HepG2 cells without inducing cytotoxicity or apoptosis. To demonstrate the specificity of drugs for K(+) channels, whole-cell patch-clamp recordings were made. Hepatocytes revealed K(+) currents with K(ATP) channel properties. These K(+) currents were augmented by minoxidil and pinacidil and attenuated by glibenclamide as well as tetraethylammonium, in agreement with established responses of K(ATP) channels. Reverse transcription of total cellular RNA followed by polymerase chain reaction showed expression of K(ATP) channel-specific subunits in rat hepatocytes and human liver cell lines. Calcium fluxes were unperturbed in glibenclamide-treated HepG2 cells and primary rat hepatocytes following induction with ATP and hepatocyte growth factor, respectively, suggesting that the effect of K(ATP) channel activity upon hepatocyte proliferation was not simply due to indirect modulation of intracellular calcium. The regulation of mitogen-related hepatocyte proliferation by K(ATP) channels advances our insights into liver growth control. The findings have implications in mechanisms concerning liver development, regeneration, and oncogenesis.
Highlights
To determine whether KATP channels control liver growth, we used primary rat hepatocytes and several human cancer cell lines for assays
KATP Channel Activity and Proliferation of Cultured Hepatocytes—Initial experiments were undertaken to analyze the effects of DNA synthesis in primary rat hepatocytes
10 ng/ml human hepatocyte growth factor (hHGF) increased DNA synthesis by 15 Ϯ 3-fold and hHGF plus 500 nM minoxidil by 32 Ϯ 6-fold above untreated control cells, whereas in response to 12.5 or 25 M quinidine, DNA synthesis induced by hHGF and minoxidil decreased to 17 Ϯ 1-fold and decreased further to 7 Ϯ 1-fold above untreated control cells with 50 M quinidine (p Ͻ 0.05, analysis of variance)
Summary
To determine whether KATP channels control liver growth, we used primary rat hepatocytes and several human cancer cell lines for assays. Reverse transcription of total cellular RNA followed by polymerase chain reaction showed expression of KATP channel-specific subunits in rat hepatocytes and human liver cell lines. Calcium fluxes were unperturbed in glibenclamide-treated HepG2 cells and primary rat hepatocytes following induction with ATP and hepatocyte growth factor, respectively, suggesting that the effect of KATP channel activity upon hepatocyte proliferation was not due to indirect modulation of intracellular calcium. Receptor-coupled, voltage-sensitive, and calcium-sensitive Kϩ channels regulate proliferation in lymphocytes, adipocytes, and epithelial cells derived from the skin, breast, bladder, and stomach [13,14,15]. We studied primary rat hepatocytes as well as several established human cancer cell lines to analyze the effects of KATP channel regulation upon cell proliferation. The results showed that KATP channels play significant roles in regulating hepatocyte proliferation
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
