Cytokines, glucose and angiotensin II (ANG II) and the expression of Connexin (Cx) 37, 40 and 43 in cultured microvascular endothelial cells

Abstract

Endothelial connexins emerge as molecules that strongly affect the conductive behavior of the endothelial cell layer and are involved in renin release in the kidney. Since many of the cardiovascular disease states are associated with micro‐inflammation and with increased activity of ANG II or with increased glucose, we hypothesized that these could affect expression levels of the connexins 37, 40 and 43. Immortalized microvascular endothelial cells (HMEC‐1) were exposed to Ang II (100 nM), a combination of IL6 (20 IU/ml), IFN (4 ng/ml) and TNFa (20 ng/ml) or to 25 mM Glucose for 4 hours in 50% and 100% confluent HMEC‐1 layers. Then, cells were harvested, RNA extracted and reverse transcribed and subjected to qPCR using pre‐designed primers for Cx37, Cx40 and Cx43 using GAPDH as control. Confluency by itself increased Cx37 expression, but did not affect Cx40 and Cx43 expression. The cytokine mix increased expression of 50% and 100% confluent cells 13‐ and 16‐fold (both P<0.05) for Cx40 and 2‐fold (P<0.05) and 2‐fold (NS) for Cx37. Neither ANG II or high glucose affected Cx expression. The present data indicate that inflammatory factors can affect the gene expression of Cx40 in particular. This might point toward a role for Cx40 in coupling inflammation to microvascular function and to renin release.