Presence of soluble and particulate guanylyl cyclase in the same hippocampal astrocytes

The localisation of particulate and soluble guanylyl cyclase was studied in hippocampal astrocytes. Counting the colocalisation of cGMP immunoreactivity with the astrocytic marker glial fibrillary acidic protein after stimulation of brain slices with sodium nitroprusside (0.1 mM) or atrial natriuretic peptide (100 nM), we were able to show that at least 67% of the hippocampal astrocytes contained both guanylyl cyclase isoforms. In addition, it was shown that a large number of atrial natriuretic peptide, brain-derived natriuretic peptide or sodium nitroprusside responsive cells contain the β1-subunit of the soluble guanylyl cyclase. The results show that, in at least a subset of hippocampal astrocytes, soluble and particulate guanylyl cyclases are simultaneously present in the same cells.