title: Effects of anions on calcium component in sensory nerve terminal of frog muscle spindles.
abstract: An increase in the Ca2+ component following individual sodium spike in spontaneous discharges was observed in the isolated sensory terminal of the frog muscle spindle perfused with isotonic sodium solution with a group of anions, of which the size in the aqueous solution ranged from 0.74 to 1.32 times that of hydrated sodium ion. The effects of these anions was counteracted with divalent cations. It is hypothesized that anions similar in size to hydrated sodium ions may form an anion-cation complex at the interaction site of the Na+ carrier, whereby the Na+ may enter the Ca2+ channel. This may be inactivated by the divalent cations.
mesh_terms: D000344:Afferent Pathways / Q000187:drug effects; D000818:Animals; D000838:Anions; D002118:Calcium / Q000378:metabolism*; D007473:Ion Channels / Q000187:drug effects*; D008564:Membrane Potentials / Q000187:drug effects; D009470:Muscle Spindles / Q000187:drug effects*; D009132:Muscles / Q000294:innervation; D011898:Ranidae; D011984:Sensory Receptor Cells / Q000187:drug effects*; D012964:Sodium / Q000494:pharmacology*
chemical_list: D000838:Anions; D007473:Ion Channels; D012964:Sodium; D002118:Calcium