Classical protein kinase C and its hypoxic stimulus-induced translocation in the cat and rat carotid body

The presence, subcellular distribution, species specificity and possible hy poxic stimulus-induced translocation of classical protein kinase C (cPKC) i sozymes were examined in the carotid body, Carotid bodies were dissected from cats exposed in vivo to normoxic or acut e hypoxic conditions and from normoxic rats. For immunohistochemistry isofo rm-specific monoclonal antisera to PKC alpha, PKC beta I, PKC beta II and P KC gamma were used, The immunoreactivity was visualized by fluorescein isot hiocyanate (FITC) labelling. FITC/Texas red double-labelled specimens for t he cPKC isozymes/tyrosine hydroxylase were used to demonstrate the chemorec eptor cell localization of cPKC isozymes, The immunofluorescence was detect ed using laser scanning confocal image technology, The results showed expression of the PKC alpha and PKC gamma but not PKC be ta isoforms in the cytoplasm of carotid body chemoreceptor cells, The doubl e labelling provided evidence for the chemoreceptor cell localization of th e cPKC isoforms detected, The immunostaining was most intense in the periph ery of the perikarya, the nuclear envelope and, occasionally, the nucleopla sm. No major differences were found in the immunolocalization of PKC alpha and PKC gamma under normoxic and hypoxic conditions or between species. How ever, the immunoreactivity tended to accumulate more in the peripheral, cyt oplasm and away from the nucleus in the hypoxic chemoreceptor cell. This study demonstrates the presence of classical protein kinase C enzymes in chemoreceptor cells, The intensity of the immunoreactivity may suggest a role for the classical protein kinase C signalling pathway in shaping the hypoxic response at the carotid body. However, this study failed to provide firm evidence of this.