Cyclic GMP-dependent protein kinase and soluble guanylyl cyclase disappear in elicited rat neutrophils.

The nitric oxide/soluble guanylyl cyclase/cGMP-dependent protein kinase (NO/sGC/PKG) cascade has been shown to affect important functions of circulating neutrophils. We demonstrate that neutrophils isolated from rats treated intraperitoneally with peptone protease cannot use this signaling pathway. Although PKG was detected at both the mRNA and protein levels in peripheral blood neutrophils (PBNs) of control rats, it was expressed neither in PBNs nor in peritoneal exudate neutrophils (PENs) of provoked rats. Also, mRNA of the alpha and beta chains of heterodimeric sGC was present in PBNs, but absent in PENs. Consistently, PBNs responded to activators of sGC with cGMP synthesis, while PENs did not. These results showed that neutrophils recruited by a provoking agent lost PKG and, in the case of PENs, also sGC and thus the capacity to respond to NO with cGMP signaling. We speculate that such downregulation of the sGC/PKG pathway is likely a result of the high activity of inducible NO synthase observed in inflammatory neutrophils.