High glucose alters connexin 43 expression and gap junction intercellular communication activity in retinal pericytes

Invest Ophthalmol Vis Sci. 2003 Dec;44(12):5376-82. doi: 10.1167/iovs.03-0360.


Purpose: To investigate the role of the gap junction protein, connexin-43 (Cx43) in the maintenance of retinal vascular homeostasis in diabetic retinopathy.

Methods: In human retinal pericytes (HRPs) and bovine retinal pericytes (BRPs) grown for 7 days in normal (5 mM) or high (30 mM)-glucose medium, the Cx43 protein level was determined by Western blot analysis. Parallel experiments were performed in HRPs to determine the Cx43 mRNA level by RT-PCR, the distribution and localization of Cx43 protein by immunostaining, and gap junction intercellular communication (GJIC) activity by a scrape-loading dye transfer technique. Distribution and localization of Cx43 protein was also determined in pericyte-endothelial cell cocultures.

Results: Western blot analysis of the Cx43 protein level in HRPs and BRPs indicated reduced Cx43 expression in the high-glucose condition (69.1% +/- 17% of control, P = 0.004; 62.3% +/- 19% of control, P = 0.001, respectively). The Cx43 mRNA level in HRPs grown in high-glucose medium also showed significant reduction (71.4% +/- 16.8% of control, P = 0.02). The relative number of Cx43 plaques indicative of Cx43 localization at specific sites of contact between adjacent cells showed significant reduction in the high-glucose condition (61% +/- 10% of control, P = 0.002); similarly, a significant reduction in the number of plaques was observed in cocultures grown in high-glucose medium compared with those in normal medium (59.4% +/- 29% of control, P = 0.001). Cells with reduced Cx43 expression showed significantly reduced transfer of lucifer yellow (61% +/- 13% of control, P = 0.001; r = 0.9).

Conclusions: High-glucose-induced downregulation of Cx43 expression and inhibition of GJIC in retinal pericytes may play a role in the disruption of vascular homeostasis in diabetic retinopathy.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Blotting, Western
  • Cattle
  • Cell Communication / drug effects*
  • Cell Culture Techniques
  • Coculture Techniques
  • Connexin 43 / genetics
  • Connexin 43 / metabolism*
  • Connexins / metabolism
  • Down-Regulation
  • Endothelium, Vascular / cytology
  • Endothelium, Vascular / metabolism
  • Fluorescent Antibody Technique, Indirect
  • Gap Junctions / drug effects*
  • Glucose / pharmacology*
  • Humans
  • Pericytes / cytology
  • Pericytes / drug effects*
  • Pericytes / metabolism
  • RNA, Messenger / metabolism
  • Retinal Vessels / cytology
  • Reverse Transcriptase Polymerase Chain Reaction


  • Connexin 43
  • Connexins
  • RNA, Messenger
  • connexin 37
  • connexin 40
  • Glucose