Alkadhi K A, Simples J E
Department of Pharmacology, College of Pharmacy, University of Houston, TX 77204-5515.
J Auton Nerv Syst. 1991 Jun 15;34(2-3):221-9. doi: 10.1016/0165-1838(91)90088-k.
The effects of the alkali metal ions cesium (Cs+) and rubidium (Rb+) and alkaline earth metal ions barium (Ba2+) and strontium (Sr2+) on ganglionic transmission in various calcium (Ca2+) concentrations were investigated in rat isolated superior cervical ganglia. Cesium (1 and 2 mM) moderately supported transmission in low Ca2+ and potentiated the compound action potential (CAP) at high Ca2+ concentration. Higher concentrations of Cs+ caused depression of CAP especially at lower Ca2+ concentration. Cesium (1-4 mM) induced large spontaneous rhythmic spikes or burst of spikes. At 4 mM, Rb+ potentiated CAP at all Ca2+ concentrations. As with Cs+, higher concentrations of Rb+ inhibited CAP except at large Ca2+ concentrations. Barium (1-6 mM) effectively enhanced transmission at all Ca2+ concentrations. Strontium enhanced transmission only at very low Ca2+ concentrations. No enhancement was seen with Sr2+ in the presence of normal or higher Ca2+. The results indicate that Cs+ and Rb+ may antagonize Ca2+ effects at release sites while allowing more Ca2+ influx into the nerve terminal as a result of K+ channel blockade. Barium and to a lesser extent Sr2+ may substitute for Ca2+ in the process of transmitter release in the superior cervical ganglia of rats.
在大鼠离体颈上神经节中，研究了碱金属离子铯（Cs +）和铷（Rb +）以及碱土金属离子钡（Ba2 +）和锶（Sr2 +）在不同钙（Ca2 +）浓度下对神经节传递的影响。铯（1和2 mM）在低Ca2 +浓度下适度支持传递，并在高Ca2 +浓度下增强复合动作电位（CAP）。较高浓度的Cs +导致CAP降低，尤其是在较低Ca2 +浓度下。铯（1 - 4 mM）诱导大量自发节律性尖峰或尖峰爆发。在4 mM时，Rb +在所有Ca2 +浓度下均增强CAP。与Cs +一样，较高浓度的Rb +抑制CAP，但在高Ca2 +浓度下除外。钡（1 - 6 mM）在所有Ca2 +浓度下均有效增强传递。锶仅在非常低的Ca2 +浓度下增强传递。在正常或较高Ca2 +存在下，Sr2 +未见增强作用。结果表明，Cs +和Rb +可能在释放位点拮抗Ca2 +的作用，同时由于钾通道阻滞而允许更多Ca2 +流入神经末梢。钡以及程度较轻的Sr2 +可能在大鼠颈上神经节递质释放过程中替代Ca2 +。
