Sakhrani L M, Tessitore N, Massry S G
Am J Physiol. 1985 Sep;249(3 Pt 2):F346-55. doi: 10.1152/ajprenal.1985.249.3.F346.
We examined the effects of acute changes in extracellular and intracellular calcium on transport processes in primary culture of proximal rabbit renal cells. A change in extracellular calcium from 0 to 3 mM inhibited amiloride-sensitive sodium uptake by 30%, and this effect was maximal at 1 mM calcium. Other polyvalent cations (Mn2+, Mg2+, La3+, and Ba2+) produced quantitatively similar inhibition of amiloride-sensitive sodium uptake compared with calcium. An increase in cytosolic calcium produced by calcium loading (20 mM) or by A23187 (20 microM) resulted in an inhibition of 25-40% of amiloride-sensitive sodium uptake. Moreover, quinidine (10(-4)M) and ruthenium red (3 microM), agents presumed to increase cytosolic calcium, inhibited amiloride-sensitive sodium uptake by 20-60%. Both these agents also inhibited sodium-dependent phosphate uptake by 20% but had no effect on ouabain-sensitive 86Rb+ uptake or on sodium-dependent alpha-methylglucoside uptake. Our data indicate that increases in extracellular calcium inhibit amiloride-sensitive sodium uptake and increases in cytosolic calcium inhibit sodium-dependent phosphate and amiloride-sensitive sodium uptakes. The effect of extracellular calcium may be due to charge screening and/or binding to the negatively charged plasma membrane or due to alterations in membrane fluidity.
我们研究了细胞外和细胞内钙的急性变化对原代培养的兔近端肾细胞转运过程的影响。细胞外钙浓度从0 mM变为3 mM可使阿米洛利敏感的钠摄取抑制30%，且此效应在钙浓度为1 mM时最大。与钙相比，其他多价阳离子（Mn2+、Mg2+、La3+和Ba2+）对阿米洛利敏感的钠摄取产生了定量相似的抑制作用。通过钙负载（20 mM）或A23187（20 μM）使胞质钙增加，导致阿米洛利敏感的钠摄取受到25%-40%的抑制。此外，奎尼丁（10-4M）和钌红（3 μM）这两种被认为会增加胞质钙的试剂，使阿米洛利敏感的钠摄取抑制了20%-60%。这两种试剂还使钠依赖性磷酸盐摄取抑制了20%，但对哇巴因敏感的86Rb+摄取或钠依赖性α-甲基葡萄糖苷摄取没有影响。我们的数据表明，细胞外钙增加会抑制阿米洛利敏感的钠摄取，而胞质钙增加会抑制钠依赖性磷酸盐摄取和阿米洛利敏感的钠摄取。细胞外钙的作用可能是由于电荷屏蔽和/或与带负电荷的质膜结合，或由于膜流动性的改变。
