(A) Effects of various concentrations of somatostatin-28
and analogs on forskolin-stimulated cAMP accumulation in cells
expressing sst3. Concentration–response curves were
obtained with increasing concentrations of somatostatin-28
(●), ODT-8 (■) or 9
(▴), and of somatostatin-28 in the presence of
10−5 M 9
(▾),10−5 M 10
(○), or 10−5 M ODT-8 (♦). Data are
expressed as a percentage of the 10 μM forskolin response. The
somatostatin analogs 9 and 10 antagonize the
concentration-dependent inhibition of cAMP accumulation by
somatostatin-28 in sst3-expressing cells.
(B) Effects of various concentrations of somatostatin
analogs in the presence of a fixed concentration of somatostatin-28 on
forskolin-stimulated cAMP accumulation in cells expressing
sst3. Concentration–response curves were
obtained with increasing concentrations of 7
(●), 10 (■), and ODT-8
(▴) in the presence of 5 × 10−8
M somatostatin-28. Data are expressed as a percentage of the 10 μM
forskolin response. The somatostatin analogs 7 and
10 concentration-dependently reverse the inhibition of cAMP
accumulation by somatostatin-28 in
sst3-expressing cells. (C) Effects of
various concentrations of 10 on somatostatin-28-stimulated
IPx accumulation in cells expressing
sst3. The concentration–response curve was
obtained with increasing concentrations of 10 in the
presence of 10−5 M somatostatin-28. Data are
expressed as a percentage of the 10 μM somatostatin-28 response.
10 antagonizes concentration-dependently the stimulation of
IPx accumulation by somatostatin-28 in
sst3-expressing cells.