Internalization and cellular processing of cholecystokinin in rat pancreatic acinar cells

Journal Article · Thu Dec 01 00:00:00 EST 1988 · American Journal of Physiology; (USA)

OSTI ID:6038736

Izzo, R S; Pellecchia, C; Praissman, M ^[1]

---

1. Nassau County Medical Center, East Meadow, NY (USA)

To evaluate the internalization of cholecystokinin, monoiodinated imidoester of cholecystokinin octapeptide ({sup 125}I-(IE)-CCK-8) was bound to dispersed pancreatic acinar cells, and surface-bound and internalized radioligand were differentiated by treating with an acidified glycine buffer. The amount of internalized radioligand was four- and sevenfold greater at 24 and 37{degree}C than at 4{degree}C between 5 and 60 min of association. Specific binding of radioligand to cell surface receptors was not significantly different at these temperatures. Chloroquine, a lysosomotropic agent that blocks intracellular proteolysis, significantly increased the amount of CCK-8 internalized by 18 and 16% at 30 and 60 min of binding, respectively, compared with control. Dithiothreitol (DTT), a sulfhydryl reducing agent, also augmented the amount of CCK-8 radioligand internalized by 25 and 29% at 30 and 60 min, respectively. The effect of chloroquine and DTT on the processing of internalized radioligand was also considered after an initial 60 min of binding of radioligand to acinar cells. After 180 min of processing, the amount of radioligand internalized was significantly greater in the presence of chloroquine compared with controls, whereas the amount of radioligand declined in acinar cells treated with DTT. Internalized and released radioactivity from acinar cells was rebound to pancreatic membrane homogenates to determine the amount of intact radioligand during intracellular processing. Chloroquine significantly increased the amount of intact {sup 125}I-(IE)-CCK-8 radioligand in released and internalized radioactivity while DTT increased the amount of intact radioligand only in internalized samples. This study shows that pancreatic acinar cells rapidly internalize large amounts of CCK-8 and that chloroquine and DTT inhibit intracellular degradation.

• OSTI ID: 6038736
• Journal Information: American Journal of Physiology; (USA), Vol. 255:6; ISSN 0002-9513
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
KININS
UPTAKE
MEMBRANE TRANSPORT
TEMPERATURE EFFECTS
IODINE 125
LIGANDS
METABOLISM
PANCREAS
PEPTIDES
RATS
ANIMALS
BETA DECAY RADIOISOTOPES
BODY
DAYS LIVING RADIOISOTOPES
DIGESTIVE SYSTEM
ELECTRON CAPTURE RADIOISOTOPES
ENDOCRINE GLANDS
GLANDS
INTERMEDIATE MASS NUCLEI
IODINE ISOTOPES
ISOTOPES
MAMMALS
NUCLEI
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
ORGANS
POLYPEPTIDES
PROTEINS
RADIOISOTOPES
RODENTS
VERTEBRATES
550201* - Biochemistry- Tracer Techniques