Journal of Neuroscience, Vol 5, 3370-3378, Copyright © 1985 by Society for Neuroscience
Functional substance P receptors on a rat pancreatic acinar cell line
MD Womack, MR Hanley and TM Jessell
A pancreatic acinar cell line, AR4-2J, that expresses a high density of
substance P (SP)-binding sites has been identified. SP-binding sites on
intact AR4-2J cells were detected with 125I-Bolton-Hunter SP (125I- BHSP).
125I-BHSP binding to AR4-2J cells has an apparent Kd of 40 pm with slow
rates of association and dissociation. The number of high affinity binding
sites was about 10(4)/cell. Binding of 125I-BHSP was inhibited by SP and by
structurally related peptides. Physalaemin was a more potent inhibitor of
binding than SP, whereas kassinin, eledoisin, and neurokinin A (substance
K, neuromedin alpha, or neurokinin L) were much less potent. SP-free acid
and SP (7-11) were 3 to 4 orders of magnitude less potent than SP itself.
The membrane, intracellular, and secretory events elicited by exposure of
AR4-2J cells to SP have also been examined. Intracellular recording from
AR4-2J cells revealed resting membrane potentials of -40 to -65 mV.
Pressure application of SP (100 pM to 100 nM) evoked depolarizations of 20
to 40 mV which were maintained for prolonged periods. The intracellular
free calcium concentration in AR4-2J cells, measured with (2-[2-amino-5-
methylphenoxy)-methyl)-6-methoxy-8-aminoquinolone tetra-acetoxy methyl
ester), was between 100 and 500 nM. Addition of SP (100 pM to 10 nM) or
physalaemin (1 nM) induced a transient rise in intracellular free calcium.
AR4-2J cells synthesize amylase, and exposure of cells to SP resulted in a
dose-dependent increase in amylase secretion.(ABSTRACT TRUNCATED AT 250
WORDS)