C. Gotti et al., NATIVE NICOTINIC ACETYLCHOLINE-RECEPTORS IN HUMAN IMR32 NEUROBLASTOMA-CELLS - FUNCTIONAL, IMMUNOLOGICAL AND PHARMACOLOGICAL PROPERTIES, European journal of neuroscience, 7(10), 1995, pp. 2083-2092
IMR32 cells express two classes of surface nicotinic receptors: those
labelled with high affinity by [I-125]neuronal toxin, and those labell
ed by [(125)]alpha-bungarotoxin. Whole-cell patch-clamp recordings ind
icate that both classes of receptor are able to elicit inward currents
that are totally blocked by d-tubocurarine but only partially blocked
by alpha-bungarotoxin. In IMR32 cells, nicotine induces an increase i
n the intracellular level of free Ca2+. This increase, which is also c
ompletely blocked by d-tubocurarine and only partially blocked by alph
a-bungarotoxin and Cd2+, is due to extracellular calcium influx throug
h both the nicotinic receptors and the voltage-activated Ca2+ channels
. By using subunit-specific polyclonal antibodies, we have demonstrate
d that the alpha-bungarotoxin receptors contain the alpha 7 subunit, b
ut none of the other subunits whose transcripts are present in IMR32 c
ells. The pharmacological profile of these human alpha 7-containing al
pha-bungarotoxin receptors is similar to that observed in the native c
hick alpha 7 receptor, but there are also some species-specific differ
ences.