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Connexin Isoform Expression in Smooth Muscle Cells and Endothelial Cells of Hamster Cheek Pouch Arterioles and Retractor Feed Arteries
Author(s) -
HAKIM CHADY H.,
JACKSON WILLIAM F.,
SEGAL STEVEN S.
Publication year - 2008
Publication title -
microcirculation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.793
H-Index - 83
eISSN - 1549-8719
pISSN - 1073-9688
DOI - 10.1080/10739680801982808
Subject(s) - immunolabeling , cheek pouch , connexin , gene isoform , gap junction , biology , microbiology and biotechnology , endothelium , anatomy , chemistry , hamster , biochemistry , immunohistochemistry , intracellular , immunology , endocrinology , gene
Objective: Gap junction channels formed by connexin (Cx) protein subunits enable cell‐to‐cell conduction of vasoactive signals. Given the lack of quantitative measurements of Cx expression in microvascular endothelial cells (EC) and smooth muscle cells (SMC), the objective was to determine whether Cx expression differed between EC and SMC of resistance microvessels for which conduction is well‐characterized. Methods: Cheek pouch arterioles (CPA) and retractor feed arteries (RFA) were hand‐dissected and dissociated to obtain SMC or endothelial tubes. In complementary experiments, small intestine was dissociated to obtain SMC. Following reverse transcription, quantitative Real‐Time Polymerase Chain Reaction (qRT‐PCR) was performed by using specific primers and fluorescent probes for Cx37, Cx40, and Cx43. Smooth muscle α‐actin (SMAA) and platelet endothelial cell adhesion molecule‐1 (PECAM‐1) served as respective reference genes. Results: Transcript copy numbers were similar for each Cx isoform in EC from CPA and RFA (∼0.5 Cx/PECAM‐1). For SMC, Cx43 transcript in CPA and RFA (<0.1 Cx/SMAA) was less (p < 0.05) than that in small intestine (∼0.4 Cx/SMAA). Transcripts for Cx37 and Cx40 were also detected in SMC. Punctate immunolabeling for each Cx isoform was pronounced at EC borders and that for Cx43 was pronounced in SMC of small intestine. In contrast, Cx immunolabeling was not detected in SMC of CPA or RFA. Conclusions: Connexin expression occurs primarily within the endothelium of arterioles and feed arteries, supporting a highly effective pathway for conducting vasoactive signals along resistance networks. The apparent paucity of Cx expression within SMC underscores discrete homocellular coupling and focal localization of myoendothelial gap junctions.