Gaspardone A, Shine K I, Seabrooke S R, Poole-Wilson P A
J Mol Cell Cardiol. 1986 Apr;18(4):389-99. doi: 10.1016/s0022-2828(86)80902-6.
To determine the effects of permeant and impermeant anions and of osmolarity on potassium (K+) exchange, the net uptake and efflux of 42K+ were recorded in the isolated arterially perfused rabbit septum. Perfusion with solution made hyperosmolar by adding NaCl (30 mM) or sucrose (60 mM) caused similar increases of 42K+ uptake which were reversible on returning to the control solution. Washout experiments showed that the loss of K+ on returning to the control perfusate was due to a decreased influx probably mediated by inhibition of the sodium pump. The effects of anions were studied by replacing chloride in the control solution with the inert and impermeant substitute isethionate (114 mM) or by loading the myocardium with sodium dimethyloxazeolidinedione (NaDMO, 30 mM) under isosmotic condition and switching to a perfusate containing sodium isethionate (30 mM). In both these conditions a reduction of 42K content could be detected and was attributable to an increased efflux. During hypoxic substrate free perfusion K+ loss was due to an increased efflux with no evidence for altered influx of potassium. The extrusion of accumulated anions from the myocardium could be the major determinant of the early potassium loss during hypoxia and ischaemia.
为了确定可渗透和不可渗透阴离子以及渗透压对钾离子（K⁺）交换的影响，在离体动脉灌注的兔心脏隔片中记录了⁴²K⁺的净摄取和流出。用添加氯化钠（30 mM）或蔗糖（60 mM）使其渗透压升高的溶液灌注，会导致⁴²K⁺摄取出现类似的增加，在恢复到对照溶液时这种增加是可逆的。洗脱实验表明，恢复到对照灌注液时钾离子的丢失是由于流入减少所致，这可能是由钠泵受抑制介导的。通过用惰性且不可渗透的替代物羟乙磺酸盐（114 mM）替代对照溶液中的氯离子，或在等渗条件下用二甲基恶唑烷二酮钠（NaDMO，30 mM）使心肌负荷，并切换到含有羟乙磺酸钠（30 mM）的灌注液来研究阴离子的影响。在这两种情况下，都可以检测到⁴²K含量的降低，这归因于流出增加。在无底物的缺氧灌注期间，钾离子的丢失是由于流出增加，没有证据表明钾离子的流入发生改变。心肌中积累的阴离子的排出可能是缺氧和缺血期间早期钾离子丢失的主要决定因素。
