Comparative Studies on the In Vitro: RESULTS(3)
As shown in Figure 3A, in baboon stromal cells, increases in IGFBP-1 levels were observed with dbcAMP alone at 12 and 17 days (1.16 ng/^g protein and 4.32 ng/^g protein, respectively) and with hormones alone at 12 and 17 days (4.31 ng/^g protein and 8.22 ng/^g protein, respectively) in comparison to basal levels with no treatment at 12 and 17 days (0.05 ng/^g protein and 0.08 ng/^g protein, respectively). Treatment with dbcAMP and hormones after 12 and 17 days caused an increase in IGFBP-1 production (31.21 ng/^g protein and 58.32 ng/^g protein, respectively; Fig. 3A) that was high enough to be detectable by Western blot analysis (data not shown). asthma inhalers
Minimal levels of IGFBP-1 protein were detected by RIA at 2 and 6 days in all treatment groups. Levels of IGFBP-1 produced by baboon stromal cells were much lower than those produced by human stromal cells. Finally, no prolactin protein was detected by RIA in the culture media of baboon stromal cells at any time (Fig. 3C). Similar results were observed in response to the other cAMP analogue, 8-bromoadenosine 3′: 5′-cyclic monophosphate, and prostaglandin E2, which increases levels of intracellular cAMP. These data rule out the potential involvement of butyrate, a metabolic by-product of dbcAMP, in stromal cell differentiation.