AJP - Gastrointestinal and Liver Physiology, Vol 241, Issue 4 313-G320, Copyright © 1981 by American Physiological Society
Prostaglandin E2-binding sites and cAMP production in porcine fundic mucosa
B. L. Tepperman and B. D. Soper
Biologically active [3H]prostaglandin E2 (PGE2) bound rapidly and
specifically to membrane fractions from hog fundic mucosa. Optimal binding
occurred in the 30,000-g membrane preparation at 37 degrees C (pH 5.0).
Scatchard analysis of specific PgE2 binding revealed the presence of a
heterogeneous population of binding sites with Kd values and binding site
concentrations of approximately 1 X 10(-9) M and 1 fmol/mg prot and 2 X
10(-8) M and 20 fmol/mg prot, respectively. Specific binding was inhibited
by the following agents in descending order of potency: PGE1, PGA2, PGD2,
6-keto-PGF1 alpha, and thromboxane B2. Trypsin treatment or boiling reduced
or abolished specific PGE2 binding. PGE2 stimulated cAMP formation in the
2,500-g fraction, with an approximate Km of 1 X 10(-6) M, but stimulation
of adenylate cyclase activity by PG was not evident in the 16,000-g or
30,000-g tissue preparations. These results suggest that a specific
PGE2-binding site exists in the 16,000-g and 30,000-g fractions of porcine
fundic mucosa, although an increase in cAMP-forming capacity could not b of
1 X 10(-6) M, but stimulation of adenylate cyclase activity by PG was not
evident in the 16,000-g or 30,000-g tissue preparations. These results
suggest that a specific PGE2-binding site exists in the 16,000-g and
30,000-g fractions of porcine fundic mucosa, although an increase in
cAMP-forming capacity could not b of 1 X 10(-6) M, but stimulation of
adenylate cyclase activity by PG was not evident in the 16,000-g or
30,000-g tissue preparations. These results suggest that a specific
PGE2-binding site exists in the 16,000-g and 30,000-g fractions of porcine
fundic mucosa, although an increase in cAMP-forming capacity could not be
localized in these fractions in vitro.
