CCK-58 is the only detectable endocrine form of cholecystokinin in rat.
CCK-58 differs from CCK-8 in patterns of expression of pancreatic secretion of fluid and amylase and gallbladder contraction. These differences have physiological relevance only if CCK-58 release is stimulated by nutrients entering the intestine and if CCK-58 circulates in sizeable amounts. In this study, we report that when radiolabeled CCK-58 is added to rat blood and plasma is formed, there is extensive loss and degradation of the radioactive peptide. Therefore, a new method was developed to minimize loss and degradation of this label. This method recovered >85% of the label with no detectable degradation. Furthermore, the optimized method recovered all unlabeled exogenous cholecystokinin molecular forms in >80% yields. Blood from fasted rats and rats in which cholecystokinin release was stimulated by the trypsin inhibitor camostat contained only CCK-58 (3.5 +/- 0.5 and 17 +/- 1.5 fmol/ml, respectively). Because CCK-58 predominates in the blood, this molecular form should be used in studies on the physiology and pathophysiology of cholecystokinin.
Reeve
Joseph R
JR
Center for Ulcer Research and Education, Veterans Affairs Greater Los Angeles Healthcare System, 90073, USA. jreeve@ucla.edu
Green
Gary M
GM
Chew
Peter
P
Eysselein
Viktor E
VE
Keire
David A
DA
D000595:Amino Acid Sequence; D000818:Animals; D002021:Buffers; D002766:Cholecystokinin / Q000097:blood* / Q000737:chemistry / Q000502:physiology; D002851:Chromatography, High Pressure Liquid; D004952:Esters; D016670:Gabexate / Q000031:analogs & derivatives* / Q000494:pharmacology; D006146:Guanidines; D006863:Hydrogen-Ion Concentration; D007457:Iodine Radioisotopes; D007553:Isotope Labeling; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000097:blood; D010940:Plant Proteins / Q000494:pharmacology; D051381:Rats; D012844:Sincalide / Q000097:blood; D014361:Trypsin Inhibitors; D014443:Tyrosine; D000516:alpha-Amylases / Q000037:antagonists & inhibitors
D002021:Buffers; D004952:Esters; D006146:Guanidines; D007457:Iodine Radioisotopes; D010446:Peptide Fragments; D010940:Plant Proteins; D014361:Trypsin Inhibitors; C034532:camostat; D014443:Tyrosine; D016670:Gabexate; C038823:cholecystokinin 58; D002766:Cholecystokinin; C044926:cholecystokinin 22 C-terminal fragment; D000516:alpha-Amylases; D012844:Sincalide