Key result
Mechanisms regulating cGMP metabolism in peritoneal macrophages are species-specific, with particulate GC-A dominating in rats and soluble GC dominating in guinea pigs.
The mechanisms regulating cGMP metabolism in peritoneal macrophages are species-specific, highlighting differences in guanylyl cyclase and phosphodiesterase activities between rats and guinea pigs.
Species differences in macrophage cGMP regulation caution against rodent-to-human extrapolation; leaves open validation in human cells.
The aim of our studies was to establish which enzymes constitute the "cGMP pathway" in rat and guinea pig peritoneal macrophages (PM). We found that in guinea pig PM synthesis of the nucleotide was significantly enhanced in response to activators of soluble guanylyl cyclase (sGC) and it was only slightly stimulated by specific activators of particulate guanylyl cyclases (pGC). In contrast, rat PM responded strongly to atrial natriuretic peptide (ANP), the activator of pGC type A. The rat cells synthesized about three-fold more cGMP than an equal number of the guinea pig cells. The activity of phosphodiesterases (PDE) hydrolyzing cGMP was apparently regulated by cGMP itself in PM of both species and again it was higher in the rat cells than in those isolated from guinea pig. However, guinea pig PM revealed an activity of Ca(2+)/calmodulin-dependent PDE1, which was absent in the rat cells. Using Western blotting analysis we were unable to detect the presence of cGMP-dependent protein kinase 1 (PKG1) in PM isolated from either species. In summary, our findings indicate that particulate GC-A is the main active form of GC in the rat PM, while in guinea pig macrophages the sGC activity dominates. Since the profiles of the PDE activities in rat and guinea pig PM are also different, we conclude that the mechanisms regulating cGMP metabolism in PM are species-specific. Moreover, our results suggest that targets for cGMP other than PKG1 should be present in PM of both species.
No takes yet. Share an insight, caveat, or question.
Kobiałka et al. (2003) studied this question. Guanylyl cyclase activators (e.g., ANP) was evaluated on cGMP synthesis and phosphodiesterase activity. Mechanisms regulating cGMP metabolism in peritoneal macrophages are species-specific, with particulate GC-A dominating in rats and soluble GC dominating in guinea pigs.
Synapse has enriched 5 closely related papers on similar clinical questions. Consider them for comparative context: