AJP - Gastrointestinal and Liver Physiology, Vol 244, Issue 3 321-G326, Copyright © 1983 by American Physiological Society
Effect of lanthanum on pancreatic protein synthesis in streptozotocin-diabetic rats
M. Korc
The role of extracellular Ca2+ in mediating the stimulatory effect of
cholecystokinin octapeptide (CCK8) on [3H]phenylalanine incorporation into
protein was studied in isolated pancreatic acini from
streptozotocin-diabetic rats. The stimulatory effect of CCK8 (10(-10) M) on
[3H]phenylalanine incorporation was completely abolished by preincubating
acini with either 10(-4) M lanthanum or 10(-3) M manganese. At these
concentrations neither compound altered the basal rate of amino acid
incorporation, and both compounds inhibited CCK-mediated Ca2+ influx
without affecting either basal or CCK-mediated 45Ca2+ efflux. Lanthanum
(10(-4) M) also blocked the stimulatory effect of the cholinergic analogue
carbachol (10(-5) M) on amino acid incorporation but did not alter the
stimulatory effect of insulin (1.67 x 10(-8) M). Vasoactive intestinal
polypeptide and 12-O-tetradecanoyl-phorbol-13-acetate failed to increase
the incorporation of [3H]phenylalanine into acinar protein. These findings
suggest that CCK and other pancreatic secretagogues that act via Ca2+
enhance protein synthesis by increasing cell membrane permeability to Ca2+
and provide additional evidence that this may be an important mechanism by
which CCK regulates pancreatic exocrine function.
