INHIBITION OF [ACETYLCHOLINE-H-3 ACTIVE-TRANSPORT BY TETRAPHENYLBORATE AND OTHER ANIONS

  • 1 January 1983
    • journal article
    • research article
    • Vol. 24  (1) , 55-59
Abstract
The effects of tetraphenylborate and other anions on the active uptake of [3H]acetylcholine by synaptic vesicles isolated from Torpedo californica electric organ were studied. Tetraphenylborate completely inhibits active uptake with a half-inhibitory concentration of 0.3 .mu.M. Dipicrylaminate half-inhibits at 0.3 .mu.M, phenyldicarbaundecaborane at 14 .mu.M, F- at 2 mM, thiocyanate at 3 mM and azide at 16 mM. Tetraphenylborate had no effect on the vesicle ATPase activity or the transmembrane electric potential at low concentrations where it inhibits [3H]acetylcholine active transport. The mechanism for tetraphenylborate inhibition is uncertain, but it might be similar to that of its action as a mitochondrial uncoupler. Solubility products for the acetylcholine, choline and K salts of the tetraphenylborate and dipicrylaminate anions were measured. The inhibition results confirm the hypothesis that tetraphenylborate acts on intact neuromuscular preparations to inhibit transmitter storage, and constitute new pharmacological evidence that evoked release of acetylcholine is mediated by synaptic vesicles.