Two types of glomus cell in the rat carotid body as revealed by ?-bungarotoxin binding

Abstract

Horseradish peroxidase (HRP)-conjugated alpha-bungarotoxin (alpha Bgt) was used to localize alpha Bgt-acetylcholine receptor sites in the rat carotid body. Two types of glomus cell were differentiated on the basis of the staining of their plasma membranes by the conjugate: type A, devoid of staining or only partly stained; and type B, exhibiting staining over the entire cell surface. The parts of type A glomus and supporting cells stained were always in direct apposition to type B glomus cells. It is concluded that type B glomus cells are possibly the only cell types exhibiting specific binding sites of alpha Bgt. Other morphological characteristics and quantitative studies indicated that the type A and type B glomus cells presented in this study were equivalent to those described in the rat carotid body by other investigators (McDonald & Mitchell, 1975). alpha Bgt-HRP staining facilitated the observation of the distribution pattern of glomus cells in the parenchyma: type A glomus cells were arranged in groups and often showed polarity toward neural elements and sinusoidal capillaries; and clusters of type B glomus cells were frequently situated in a demilune -like fashion over groups of type A glomus cells. Because of differences in morphology, synaptology, alpha Bgt-binding affinity, and polarity toward the blood vessels, we propose that type A and type B glomus cells in the rat carotid body represent functionally distinct cell types.

Fast neurogenesis from carotid body quiescent neuroblasts accelerates adaptation to hypoxia

“…As both neuroblasts and glomus cells are TH + , it is for this reason that they were not distinguished in previous immunocytochemical analyses. The existence of two glomus cell classes in the CB had, however, been suggested in previous morphometric studies . Interestingly, one of the cell subtypes reported in those studies, with a smaller size and a reduced number and volume of secretory vesicles, as well as a peripheral location within glomeruli , corresponds to the pre‐differentiated neuroblasts reported here.…”

Short-term Hypoxia Transiently Increases Dopamine β-Hydroxylase Immunoreactivity in Glomus Cells of the Rat Carotid Body

“…It has been reported that glomus cells are divided into cell subpopulations based on the size of dense-cored vesicles and/or innervations (McDonald and Mitchell 1975;Hansen 1981) and α-bungarotoxin binding affinity (Chen and Yates 1984). In the present study, both DBHimmunopositive glomus cells and DBH-immunonegative glomus cells were observed in all experimental groups based on GI values.…”

Peripheral Chemoreceptors: Function and Plasticity of the Carotid Body

“…Further, the specific distinction into type A and type B cells with possible different functions (565), was endorsed by a study in which α-bungarotoxin was used to distinguish ACh receptor binding sites on type I cells with the finding that type A cells showed little or no binding whilst type B cells showed plentiful binding distributed across the entire cell surface (142). These authors, as had McDonald and Mitchell previously (565, 566), suggested that the difference in cell type might demonstrate a difference in function with only type A cells acting as the presynaptic elements in a composite receptor system.…”