NICOTINE-INDUCED INTRACELLULAR CALCIUM CHANGES ARE NOT ANTAGONIZED BYALPHA-BUNGAROTOXIN IN ADRENAL-MEDULLARY CELLS

The snake toxin alpha-bungarotoxin distinguishes between neuronal nico tinic receptor subtypes. In chick ciliary ganglion neurons, activation of alpha-bungarotoxin-sensitive nicotinic receptors has been proposed to produce elevations in intracellular calcium levels. In the present study we show that prolonged treatment with alpha-bungarotoxin did no t affect the nicotine-evoked calcium response in suspended chromaffin cells. On the other hand, the classical nicotinic receptor blocker d-t ubocurarine potently blocked nicotinic receptor mediated effects. The degree of inhibition of the nicotinic response observed with d-tubocur arine was not modified by prior treatment with alpha-bungarotoxin. The se results suggest that nicotinic alpha-bungarotoxin receptors are not primarily involved in nicotine-mediated increases in intracellular ca lcium in bovine adrenal medullary cells.