Prostaglandin E1 Receptor Binding in Human Blood Platelets Stimulation and Inhibition of Adenylate Cyclase
Abstract
Prostaglandin El , E2 , Fl and. F2 stimulation of
adenylate cyclase to produce cyclic Ar~lP was studied in
human. blood platelets. L-norepinephrine, an alpha
adrenergic agonist in platelets, inhibits the production
of cyclic AMP stimulated by PGE1 by increasing the
apparent Km of PGE1. This seems to indicate that the
I-norepinephrine is decreasing the affinity PGEl has
for stimulating adenylate cyclase. Investigations in the
mode of action of prostaglandin stimulation of adenylate
cyclase revealed a membrane bound receptor site for PGE1 -
Binding studies supported by cAMP assays showed that PGE1
and PGE2 may share a co~~on receptor site while ,there may
exist a separate PGF receptor site. L-norepinephrine was
shown not to affect binding of PGE1, which provides evidence
that the inhibition of the alpha-adrenergic agonist may be
. directly on the adenylate cyclase system.