The effects of various gastrins on intracellular free Ca2+ in isolated pig parietal cells.
Gastrin 17 (G17) is a potent stimulant of gastric acid secretion in vivo. In this study, the effects of G17 and some related peptides on intracellular free Ca2+ in isolated pig parietal cells were studied. Both G17 and the synthetic peptide pentagastrin increased intracellular free Ca2+ in a dose-dependent manner over the concentration range 10(-9) to 10(-6) M, suggesting a specific action. The EC50 values were 3 X 10(-8) M for G17 and 8 X 10(-8) M for pentagastrin. The N-terminal tridecapeptide of G17 [(1-13)G17] did not have any effect on intracellular free Ca2+, nor was it able to inhibit the action of G17. A glycine-extended gastrin [(5-17)G17-Gly)] elicited a small but significant increase in intracellular free Ca2+ although only at 10(-6) M. This increase was approximately 20% of that obtained with a similar concentration of G17. Sequential incubations with (5-17)G17-Gly and G17 showed that both peptides increased the intracellular free Ca2+ through the same mechanisms.
Cabero
J L
JL
Department of Medical and Physiological Chemistry, Biomedical Centre, Uppsala University, Sweden.
Rehfeld
J F
JF
Mårdh
S
S
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002469:Cell Separation; D003600:Cytosol / Q000378:metabolism; D005110:Extracellular Space / Q000378:metabolism; D005755:Gastrins / Q000494:pharmacology*; D010295:Parietal Cells, Gastric / Q000378:metabolism*; D010418:Pentagastrin / Q000494:pharmacology*; D013552:Swine
D005755:Gastrins; C013550:gastrin 17; D010418:Pentagastrin; D002118:Calcium