Hijioka T, Goto M, Lemasters J J, Thurman R G
Department of Pharmacology, University of North Carolina, Chapel Hill 27599-7365.
Hepatology. 1993 Aug;18(2):400-5.
Kupffer cells, the resident hepatic macrophages, are activated by calcium, and several reports indicate that their function (e.g., phagocytosis and cytokine production) is altered by ethanol. We recently found that Kupffer cells contain L-type voltage-dependent Ca2+ channels. The purpose of this study, therefore, was to evaluate the effect of short-term ethanol treatment on voltage-dependent Ca2+ channels in Kupffer cells. Kupffer cells were isolated from rats 2 hr after intragastric administration of ethanol (5 gm/kg intragastrically). Cytosolic free calcium concentration of cultured Kupffer cells was measured with the fluorescent Ca2+ indicator fura-2. In Kupffer cells isolated from control rats, partial replacement of extracellular Na+ by K+ caused an increase in cytosolic free calcium concentration in a concentration-dependent manner (half-maximal effect was observed with 81 mmol/L K+), presumably because of membrane depolarization. Acute ethanol treatment in vivo shifted the concentration-response curve for K+ to the right (half-maximal effect was observed with 94 mmol/L K+) and reduced the maximal elevation of cytosolic free calcium concentration by means of K+. Significantly, the dihydropyridine-type calcium channel agonist BAY K 8644 (1 mumol/L) shifted the concentration-response curve for K+ to the left in control and ethanol-treated groups (half-maximal effect was observed with 61 and 77 mmol/L K+, respectively). Moreover, the dihydropyridine-type calcium channel blocker nitrendipine (10 mumol/L) prevented the increase in cytosolic free calcium concentration in both groups. When extracellular Ca2+ was omitted from the incubation medium, the increases in cytosolic free calcium concentration due to depolarization were prevented completely. However, direct addition of ethanol to the cell cultures was without effect.(ABSTRACT TRUNCATED AT 250 WORDS)
库普弗细胞，即肝脏中的常驻巨噬细胞，可被钙激活，并且有几份报告表明，乙醇会改变它们的功能（如吞噬作用和细胞因子产生）。我们最近发现库普弗细胞含有L型电压依赖性钙通道。因此，本研究的目的是评估短期乙醇处理对库普弗细胞中电压依赖性钙通道的影响。在大鼠胃内给予乙醇（5克/千克胃内给药）2小时后分离出库普弗细胞。用荧光钙指示剂fura-2测量培养的库普弗细胞的胞质游离钙浓度。在从对照大鼠分离的库普弗细胞中，用K+部分替代细胞外Na+会导致胞质游离钙浓度以浓度依赖性方式增加（在81毫摩尔/升K+时观察到半数最大效应），这可能是由于膜去极化。体内急性乙醇处理使K+的浓度-反应曲线向右移动（在94毫摩尔/升K+时观察到半数最大效应），并通过K+降低了胞质游离钙浓度的最大升高。值得注意的是，二氢吡啶型钙通道激动剂BAY K 8644（1微摩尔/升）在对照组和乙醇处理组中使K+的浓度-反应曲线向左移动（分别在61和77毫摩尔/升K+时观察到半数最大效应）。此外，二氢吡啶型钙通道阻滞剂尼群地平（10微摩尔/升）可防止两组胞质游离钙浓度的增加。当孵育培养基中省略细胞外Ca2+时，由于去极化导致的胞质游离钙浓度增加被完全阻止。然而，直接向细胞培养物中添加乙醇则没有效果。（摘要截短于250字）
