Characterization of ectonucleotidase expression in the rat carotid body: Regulation by chronic hypoxia

Shaima Salman, Cathy Vollmer, Grant B. McClelland, Colin A. Nurse

Research output: Contribution to journalArticlepeer-review


The carotid body (CB) chemoreflex maintains blood PO2 and PCO2/H+ homeostasis and displays sensory plasticity during exposure to chronic hypoxia. Purinergic signaling via P1 and P2 receptors plays a pivotal role in shaping the afferent discharge at the sensory synapse containing catecholaminergic chemoreceptor (type I) cells, glial-like type II cells, and sensory (petrosal) nerve endings. However, little is known about the family of ectonucleotidases that control synaptic nucleotide levels. Using quantitative PCR (qPCR), we first compared expression levels of ectonucleoside triphosphate diphosphohydrolases (NTPDAses1,2,3,5,6) and ecto-5′-nucleotidase (E5′Nt/CD73) mRNAs in juvenile rat CB vs. brain, petrosal ganglia, sympathetic (superior cervical) ganglia, and a sympathoadrenal chromaffin (MAH) cell line. In whole CB extracts, qPCR revealed a high relative expression of surface-located members NTPDase1,2 and E5′Nt/CD73, compared with low NTPDase3 expression. Immunofluorescence staining of CB sections or dissociated CB cultures localized NTPDase2,3 and E5′Nt/CD73 protein to the periphery of type I clusters, and in association with sensory nerve fibers and/or isolated type II cells. Interestingly, in CBs obtained from rats reared under chronic hypobaric hypoxia (~60 kPa, equivalent to 4,300 m) for 5-7 days, in addition to the expected upregulation of tyrosine hydroxylase and VEGF mRNAs, there was a significant upregulation of NTPDase3 and E5′Nt/CD73 mRNA, but a downregulation of NTPDase1 and NTPDase2 relative to normoxic controls. We conclude that NTPDase1,2,3 and E5′Nt/CD73 are the predominant surface-located ectonucleotidases in the rat CB and suggest that their differential regulation during chronic hypoxia may contribute to CB plasticity via control of synaptic ATP, ADP, and adenosine pools.

Original languageEnglish (US)
Pages (from-to)C274-C284
JournalAmerican Journal of Physiology - Cell Physiology
Issue number3
StatePublished - Sep 2017
Externally publishedYes


  • Ecto-5′-nucleotidase/CD73
  • Hypoxia
  • NTPDase1,2,3

ASJC Scopus subject areas

  • Physiology
  • Cell Biology


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