Cyclic AMP levels and their regulation by prostaglandins in peritoneal macrophages of rats and humans.

Basal levels of cyclic AMP and their alterations following stimulation by prostaglandins have been examined in rat peritoneal macrophages and in such cells of humans with renal disease on continuous ambulatory peritoneal dialysis (CAPD). Resident cells of rats contained more cyclic AMP than elicited macrophages, but the responsiveness to either PGE2 or DC-PGI2 (a stable synthetic analogue of PGI2) was higher with elicited than with resident cells. However, both kinds of peritoneal macrophages of rats were, in terms of cyclic AMP elevation, more sensitive to stimulation by PGE2 than by DC-PGI2. The CAPD macrophages of humans were elicited cells. The unstimulated levels of cyclic AMP in these human macrophages were much higher than those in elicited rat cells. Furthermore the human macrophages proved more sensitive to stimulation by DC-PGI2 than by PGE2. The reversed sensitivity, in comparison with rat cells, reflects the utterly poor effects of PGE2 in the human macrophages. The distinction in responsiveness to PGE2 and DC-PGI2 of the rat macrophages is compatible with the earlier reported distribution of and affinity to receptor binding sites of these PGs in the rat cells. The findings with the human macrophages suggest, however, that in these cells either the distribution of specific binding sites or the affinity of the two PGs to such sites might be substantially different from that of rats.