Distinct hyperpolarizing and relaxant roles for gap junctions and endothelium-derived H2O2 in NO-independent relaxations of rabbit arteries.

ABSTRACT: We have compared the contributions of gap junctional communication and chemical signaling via H2O2 to NO-independent relaxations evoked by the Ca2+ ionophore A23187 and acetylcholine (ACh) in rabbit ilio-femoral arteries. Immunostaining confirmed the presence of connexins (Cxs) 37 and 40 in the endothelium and Cxs 40 and 43 in smooth muscle. Maximal endothelium-dependent subintimal smooth muscle hyperpolarizations evoked by A23187 and ACh were equivalent (approximately 20 mV) and almost abolished by an inhibitory peptide combination targeted against Cxs 37, 40, and 43. However, maximal NO-independent relaxations evoked by A23187 were unaffected by such peptides, whereas those evoked by ACh were depressed by approximately 70%. By contrast, the enzyme catalase, which destroys H2O2, attenuate

SUBMITTER: Chaytor AT 

PROVIDER: S-EPMC299961 | biostudies-literature | 2003 Dec

REPOSITORIES: biostudies-literature