title: Recording of intracellular Ca2+ from smooth muscle cells by sub-micron tip, double-barrelled CA2+-selective microelectrodes.
abstract: Novel, double-barrelled Ca2+-selective microelectrodes with tip diameters of approximately 0.1 micron were constructed by using Simon's neutral Ca2+ ligand (ETH 1001). Concentric micropipettes were utilized for the first time for Ca2+-selective microelectrodes in which the Ca2+ ligand was incorporated into a protruding inner pipette, surrounded by an outer reference electrode. In addition, they were made from high resistance aluminosilicate glass tubing (Corning Code 1724). These Ca2+-selective electrodes had linear responses from pCa 3 to pCa 7 in the presence of constant [K+]. They provided on-line observation of changes in intracellular [Ca2+] and in the resting membrane potential in single smooth muscle cells isolated from toad stomach. The mean concentration of intracellular Ca2+ in resting cells was 163.6 +/- 20 nM (+/- SEM, n = 16). Doubling the intracellular Ca2+ level by exposure of cells to elevated [K+] was sufficient to cause shortening.
mesh_terms: D000818:Animals; D002024:Bufo marinus; D002118:Calcium / Q000032:analysis*; D002469:Cell Separation; D008564:Membrane Potentials; D008722:Methods; D008839:Microelectrodes / Q000592:standards; D008855:Microscopy, Electron, Scanning; D009130:Muscle, Smooth / Q000032:analysis* / Q000502:physiology; D013270:Stomach / Q000166:cytology
chemical_list: D002118:Calcium