The non-selective cation channels TRPC3 and TRPC6 in the human carotid body in the elderly

The carotid body is important in cardiovascular (patho)physiology as well as Canonical Transient Receptor Potential channel 3 and 6 (TRPC3, TRPC6). However, TRPC3 and TRPC6 were found in the rodent carotid body, whereas their distribution in the human carotid body has yet to be described. Thus, the present exploratory study aims to describe the protein distribution of TRPC3 and TRPC6 in the elderly.

The carotid body of six body donors (median age 86.5 years; 1 male, 5 female) was assessed. Hematoxylin-eosin and Movat-Pentachrome staining were applied. TRPC3 and TRPC6 were immunohistochemically labelled. If further serial sections were available, a group of differentiation 34, neurofilament, and tyrosine hydroxylase were immunohistochemically labelled to allow further morphological assessment. The immunoreactivity of TRPC3 and TRPC6 was semiquantitatively described and measured using a densitometric approach. A histomorphological assessment describing the degeneration of the carotid body and a histomorphometrical assessment that approximates the dimension of this organ served as a morphological background for the immunohistochemical analysis.

In all samples, immunoreactivity was observed primarily in the chief cells and endothelial cells. The sustentacular cells showed a less intense signal. Two body donors exhibited severe atherosclerotic degeneration and fibrosis.

The findings could be a hint that TRPC3 and TRPC6 are part of a response to carotid body hypoperfusion and fibrosis. Due to the small sample size and the utilisation of elderly and multimorbid body donors, more studies are needed to differentiate between age-associated and disease-related alterations in the expression and distribution of TRPC3 and TRPC6 in the carotid body.