AJP - Gastrointestinal and Liver Physiology, Vol 251, Issue 3 293-G299, Copyright © 1986 by American Physiological Society
Effect of Bt2cGMP on action of cholecystokinin in isolated perfused rat pancreas
M. Otsuki, Y. Okabayashi, A. Ohki, T. Nakamura, S. Tani, M. Fujii, T. Oka, H. Sankaran and S. Baba
We have examined the effects of Bt2cGMP on cholecystokinin stimulation of
pancreatic exocrine secretion in the isolated perfused rat pancreas.
Bt2cGMP produced a concentration-dependent inhibition of the stimulatory
effects of cholecystokinin octapeptide (CCK-8, 100 pM) on both pancreatic
juice flow and enzyme secretion. Adding 1 mM Bt2cGMP rapidly and completely
abolished CCK-8-stimulated pancreatic juice and enzyme secretion. Adding
500 microM Bt2cGMP for 10 min at the termination of 1 nM of CCK-8 infusion
caused an immediate and persistent inhibition of the residual response. In
contrast, treatment with C-terminal CCK antiserum I had no influence on the
residual response. To account for the ability of Bt2cGMP to function as a
competitive antagonist of the action of CCK and the ability of the
nucleotide to inhibit the residual stimulation caused by CCK, we feel that
Bt2cGMP hindered the binding of CCK not only by reducing the association
rate constant for hormone binding but also accelerating the dissociation
rate.
