| Summary: | 碩士 === 國立成功大學 === 生理學研究所 === 87 === Endothelial cells lining the inner surface of blood vessels act as a transducing surface for many physiological functions, such as controlling the permeability of blood-tissue interface, adjusting the vascular diameter according to hemodynamic needs, and modulating of the function of white blood cells and platelets. In the last decade, many channels have been described in endothelial cells, which are generally regarded as non-excitable cells. These channels control various ion permeabilities and change membrane potential, and thus modulate electrochemical driving force for Ca2+ movements. Activation of endothelial cells is usually coupled to an elevation in cytosolic Ca2+. It has been reported that blocking of K+ or Cl- channels may influence extracelluar Ca2+ influx. In this study, we have applied both conventional whole-cell patch-clamp and cell-attached perforated-patch techniques to examine electrophysiological characteristics of cultured and freshly isolated human umbilical vein endothelial cells (HUVECs). Our results showed that: (1) electrophysiological characteristics in HUVEC were different among three preparations, and these cells could be divided into four different types according to their I-V curves; (2) histamine induced an outward current and caused membrane hyperpolarization, and the cultured cells were more sensitive to histamine treatment than freshly isolated cells; (3) collagenase treatment during HUVEC isolation might damage cell membrane and reduced its sensitivity to histamine; (4) none of these three HUVEC preparations showed acetylcholine-induced membrane currents.
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