RT Journal Article
SR Electronic
T1 Tetrodotoxin-insensitive Na+ channel activator palytoxin inhibits tyrosine uptake into cultured bovine adrenal chromaffin cells.
JF Molecular Pharmacology
JO Mol Pharmacol
FD American Society for Pharmacology and Experimental Therapeutics
SP 112
OP 117
VO 40
IS 1
A1 K Morita
A1 K Teraoka
A1 M Azuma
A1 M Oka
A1 S Hamano
YR 1991
UL http://molpharm.aspetjournals.org/content/40/1/112.abstract
AB The effects of the tetrodotoxin-insensitive Na+ channel activator palytoxin on both the secretion of endogenous catecholamines and the formation of 14C-catecholamines from [14C]tyrosine were examined using cultured bovine adrenal chromaffin cells. Palytoxin was shown to cause the stimulation of catecholamine secretion in a concentration-dependent manner. However, this toxin caused the reduction rather than the stimulation of 14C-catecholamine formation at the same concentrations. Palytoxin failed to cause any alteration in the activity of tyrosine hydroxylase prepared from bovine adrenal medulla. Furthermore, the uptake of [14C]tyrosine into the cells was shown to be inhibited by this toxin under the conditions in which the suppression of 14C-catecholamine formation was observed, and this inhibitory action on tyrosine uptake was closely correlated with that on catecholamine formation. The inhibitory action of palytoxin on tyrosine uptake into the cells was observed to be noncompetitive, and this effect was not altered by the removal of Na+ from the incubation mixture. These results suggest that palytoxin may be able to inhibit the uptake of [14C]tyrosine into the cells, resulting in the suppression of 14C-catecholamine formation, probably through its direct action on the plasma membranes of bovine adrenal chromaffin cells.