Functional substance P receptors on a rat pancreatic acinar cell line.
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)
Womack
M D
MD
Hanley
M R
MR
Jessell
T M
TM
D000681:Amylases / Q000378:metabolism; D000818:Animals; D002118:Calcium / Q000378:metabolism; D002460:Cell Line; D004594:Electrophysiology; D007457:Iodine Radioisotopes; D010179:Pancreas / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D018040:Receptors, Neurokinin-1; D017981:Receptors, Neurotransmitter / Q000378:metabolism* / Q000502:physiology; D013373:Substance P / Q000378:metabolism / Q000494:pharmacology; D013388:Succinimides / Q000378:metabolism; D013997:Time Factors
C043194:Bolton Hunter reagent-substance P conjugate; D007457:Iodine Radioisotopes; D018040:Receptors, Neurokinin-1; D017981:Receptors, Neurotransmitter; D013388:Succinimides; D013373:Substance P; D000681:Amylases; D002118:Calcium