• 作者： 楊忠謀; 楊生湳
• 作者服務機構： 國防醫學院生理學科
• 中文摘要： 運用鈉選擇性電極與傳統電極同時記錄蛙縫匠肌細胞膜電位與胞內鈉離子活性。當細胞外液鈉離子濃度依序減少20％，40％，60％和80％時，細胞膜電位變化不一致，統計上並無意義；細胞內鈉活性則顯著地減少，由控制組10.0±1.1mM依序降為7.8±1.1 mM, 7．111.4mM, 6.5±1.2mM和5.9±1.1mM。另外，在細胞外液鈉離子濃度不變的情況下，提高鉀離子的濃度，由2mM增加到12mM，32mM，62mM，使細胞膜電位去極化，從控制組-87.2±1.6mV依序分別減少為-62.4±3.6mV，-45.4±3.OmV與-27.2±1.8mV。同時，細胞內鈉離子活性從控制組10.5±1.4mM，依序降低為7.3±1.6mM，6.4±1.1mM，和5.210.8mM。綜合結果顯示，細胞內鈉離子活性受到細胞膜電位與細胞外鈉離子濃度兩因素的調節；降低細胞外鈉離子濃度或細胞膜電位，均會造成細胞內鈉離子的減少。
• 英文摘要： To explore the regulation of cytosolic sodium ion activity in the frog sartorius, we used Na -selec-tive microelectrodes to monitor intracellular sodium ion activity in situations of lowering external sodiumconcentration and elevating external potassium concentration．Reductions of 20%, 40%, 60% and 80% inextraceilular sodium concentration produced slight but statistically insignificant changes in the membranepotential of the muscle. However, cytosolic sodium ion activity decreased significantly from 10.0±1.1mM to 7.8±1.1 mM，7.1±1.4 mM, 6.5±1.2 mM and 5.9±1.1 mM, respectively. In addition, elevationof the external potassium concentration from 2 mM to 12 mM, 32 mM and 62 mM caused respective step-wise depolarization of membrane potential from -87.2±1.6 mV to -62.4±3.6 mV, -45.4±3.0 mV,-27.2±1.8 mV. Under these conditions, the cytosolic sodium ion activity decreased from 10.5±1.4 mM to 7.3±1.6 mM, 6.4±1.1 mM and 5.2±0.8 mM, respectively. The results illustrate that the net sodium flux isout of cell either in the reduction of sodium chemical gradient or in the potassium depolarization across thecell membrane.
• 中文關鍵字： cytosolic sodium; skeletal muscle; potassium
• 英文關鍵字： --