Calbindin D-28k immunoreactive nerve fibers in the carotid body of normoxic and chronically hypoxic rats.
The distribution and ultrastructural characteristics of calbindin D-28k immunoreactive nerve fibers were examined in the carotid body of the normoxic control rats by light and electron microscopy, and the abundance of calbindin D-28k fibers in the carotid body was compared in normoxic and chronically hypoxic rats (10% O2 and 3.0-4.0% CO2 for 3 months). Calbindin D-28k immunoreactivity was recognized in nerve fibers within the carotid body. Calbindin D-28k immunoreactive nerve fibers appeared as thin processes with many varicosities. They were distributed around clusters of glomus cells, and around blood vessels. Immunoelectron microscopy revealed that the calbindin D-28k immunoreactive nerve terminals are in close apposition with the glomus cells, and membrane specialization is visible in some terminals. Some dense-cored vesicles in the glomus cells were aggregated in this contact region. The chronically hypoxic carotid bodies were found to be enlarged several fold, and a relative abundance of calbindin D-28k fibers was lesser than in the normoxic carotid bodies. When expressed by the density of varicosities per unit area of the parenchyma, the density of calbindin D-28k fibers associated with the glomus cells in chronically hypoxic carotid bodies was decreased by 70%. These immunohistochemical findings indicate a morphological basis for involvement of calcium binding protein in the neural pathway that modulates carotid body chemoreception.
Kusakabe
T
T
Department of Sport and Medical Science, Kokushikan University, Tokyo, Japan. kusakabe@kokushikan.ac.jp
Matsuda
H
H
Hirakawa
H
H
Hayashida
Y
Y
Ichikawa
T
T
Kawakami
T
T
Takenaka
T
T
D000818:Animals; D064026:Calbindins; D002344:Carotid Body / Q000166:cytology / Q000378:metabolism* / Q000473:pathology; D002908:Chronic Disease; D000860:Hypoxia / Q000378:metabolism* / Q000473:pathology; D007150:Immunohistochemistry; D009412:Nerve Fibers / Q000378:metabolism*; D019001:Nitric Oxide Synthase / Q000378:metabolism; D052248:Nitric Oxide Synthase Type I; D051381:Rats; D017208:Rats, Wistar; D064030:S100 Calcium Binding Protein G / Q000378:metabolism*; D014446:Tyrosine 3-Monooxygenase / Q000378:metabolism
D064026:Calbindins; D064030:S100 Calcium Binding Protein G; D019001:Nitric Oxide Synthase; D052248:Nitric Oxide Synthase Type I; C496322:Nos1 protein, rat; D014446:Tyrosine 3-Monooxygenase