Chronic hypoxia upregulates connexin43 expression in rat carotid body and petrosal ganglion.
Recent studies have demonstrated that oxygen-sensitive type I cells in the carotid body express the gap junction-forming protein connexin43 (Cx43). In the present study, we examined the hypothesis that chronic exposure to hypoxia increases Cx43 expression in type I cells as well as in chemoafferent neurons in the petrosal ganglion. Immunocytochemical studies in tissues from normal rats revealed diffuse and granular Cx43-like immunoreactivity in the cytoplasm of type I cells and dense punctate spots of immunoreactive product at the margins of type I cells and near the borders of chemosensory cell lobules. Cx43-like immunoreactivity was not detectable in petrosal ganglion neurons from normal animals. After a 2-wk exposure to hypobaric (380 Torr) hypoxia, Cx43 immunostaining was substantially enhanced in and around type I cells. Moreover, chronic hypoxia elicited the expression of Cx43-like immunoreactivity in the cytoplasm of afferent neurons throughout the petrosal ganglion. Quantitative RT-PCR studies indicate that chronic hypoxia evokes a substantial increase in Cx43 mRNA levels in the carotid body, along with a marked elevation of Cx43 expression in the petrosal ganglion. Increased Cx43 expression and gap junction formation in type I cells and sensory neurons may contribute to carotid body adaptation during sustained stimulation in extreme physiological conditions.
Chen
J
J
Department of Physiology, University of Utah, Salt Lake City, Utah 84108, USA.
He
L
L
Dinger
B
B
Stensaas
L
L
Fidone
S
S
D000199:Actins / Q000235:genetics; D000222:Adaptation, Physiological / Q000502:physiology; D000818:Animals; D002344:Carotid Body / Q000737:chemistry / Q000378:metabolism*; D002908:Chronic Disease; D018031:Connexin 43 / Q000032:analysis / Q000235:genetics* / Q000378:metabolism; D005725:Ganglia, Autonomic / Q000737:chemistry / Q000378:metabolism; D017629:Gap Junctions / Q000737:chemistry / Q000378:metabolism; D015870:Gene Expression / Q000502:physiology; D005930:Glossopharyngeal Nerve / Q000737:chemistry / Q000378:metabolism*; D000860:Hypoxia / Q000378:metabolism*; D007150:Immunohistochemistry; D008297:Male; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015854:Up-Regulation / Q000502:physiology
D000199:Actins; D018031:Connexin 43; D012333:RNA, Messenger