ADRENERGIC, CHOLINERGIC, AND INACTIVE HUMAN NEUROBLASTOMA CELL LINES WITH ACTION-POTENTIAL NA+ IONOPHORE

Abstract

Cultured human neuroblastoma cell lines were assayed for biochemical characteristics of neuronal function. Cell lines studied included LA-N-1, LA-N-2, IMR-32, SK-N-SH and SK-N-MC. Veratridine dependent uptake of 22Na+ implied the presence of the action potential Na+ ionophore in LA-N-1, LA-N-2, IMR-32 and SK-N-SH. The time course of 22Na+ uptake and inhibition of uptake by tetrodotoxin supported this. SK-N-MC had no veratridine dependent 22Na+ uptake. Tyrosine hydroxylase (EC 1.14.10), glutamic acid decarboxylase (EC 4.1.1.15) and acetylcholine content in neuroblastoma cells were compared to those in brain. LA-N-1 and IMR-32 contained 15 and 5 times as much tyrosine hydroxylase, respectively, whereas LA-N-2, SK-N-SH and SK-N-MC contained only 0.5-5% of that in brain. Acetylcholine was present in LA-N-2 in 15- to 20-fold greater quantities than in brain. Other lines had only 10-50% of that in brain. None of the cell lines contained glutamic acid decarboxylase. Continuously propagated human neuroblastoma cell lines may have the action potential Na+ ionophore and may be adrenergic (LA-N-1 and IMR-32), cholinergic (LA-N-2) or inactive (SK-N-SH and SK-N-MC). This is the 1st demonstration of the action potential Na+ ionophore and acetylcholine production in human neuroblastoma cell lines.