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1 Department of Anesthesiology and Pain Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Korea, Republic of
2 Center For Anesthesiology Research, The Clevelandclinic Foundation, Cleveland, Ohio, United States
3 Center for Anesthesiology Research, The Cleveland Clinic Foundation, Cleveland, Ohio, United States
* To whom correspondence should be addressed. E-mail: murrayp{at}ccf.org.
We assessed the roles of the protein kinase C (PKC) and the tyrosine kinase (TK) signaling pathways in regulating capacitative calcium entry (CCE) in human PASMCs, and investigated the effects of intravenous anesthetics (midazolam, propofol, thiopental, ketamine, etomidate, morphine and fentanyl) on CCE in human PASMCs. Fura-2 loaded human PASMCs were placed in a dish (37 °C) on an inverted fluorescence microscope. Intracellular Ca2+ concentration ([Ca2+]i) was measured as the 340/380 fluorescence ratio in individual PASMCs. Thapsigarigin, a sarcoplasmic reticulum Ca2+-adenosine triphosphatase inhibitor, was used to deplete intracellular Ca2+ stores after removing extracellular Ca2+. CCE was then activated by restoring extracellular Ca2+ (2.2 mM). The effects of PKC activation and inhibition, TK inhibition and the intravenous anesthetics on CCE were assessed. Thapsigargin caused a transient increase in [Ca2+]i. Restoring extracellular Ca2+ caused a rapid peak increase in [Ca2+]i, followed by a sustained increase in [Ca2+]i; i.e. CCE was stimulated in human PASMCs. PKC activation attenuated (p<0.05), whereas PKC inhibition potentiated (p<0.05) both peak and sustained CCE. TK inhibition attenuated (p<0.05) both peak and sustained CCE. Midazolam, propofol, and thiopental each attenuated (p<0.05) both peak and sustained CCE, whereas ketamine, etomidate, morphine, and fentanyl had no effect on CCE. Our results suggest that CCE in human PASMCs is influenced by both the TK and PKC signaling pathways. Midazolam, propofol, and thiopental each attenuated CCE, whereas ketamine, etomidate, morphine and fentanyl had no effect on CCE.
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