Carotid body remodelling in l-NAME-induced hypertension in the rat.

The carotid body (CB) is a chemoreceptor organ located at the bifurcation of the common carotid artery. It is made up of the carotid glomus, a structure containing type 1 cells surrounded by type 2 cells. The aim of this study was to evaluate the morphological changes of the CB and carotid glomus in the rat model of l-NAME-induced hypertension. Male Wistar rats were divided in two groups: control untreated rats (C) and rats receiving l-NAME 40 mg/kg/day (LN) for 6 weeks. At the end of the experiment, the systolic blood pressure was 63% higher in the LN group compared with the C group. Morphometric analysis showed that the area of the CB was 29% greater in the LN group compared with the C group. The density of nuclei in the CB was similar between groups, but it was 31% less in the carotid glomus of the LN group. Cells in the CB of the LN group displayed cytoplasmic vacuolation and expressed several biogenic amines. There were more elastic fibres, proteoglycans and collagen fibres in the LN group compared with the C group. Immunohistochemistry showed increased expression of nuclear factor kB, substance P, vascular endothelial growth factor and neuronal nitric oxide synthase in the LN group, while expression of the protein gene product 9.5 was decreased. l-NAME alters cell morphology and the expression of extracellular matrix molecules in the CB and carotid glomus in rats with l-NAME-induced hypertension.