Heparin-binding Egf-like Growth Factor Mediates Oxyhemoglobin-induced Suppression of Voltage-dependent Potassium Channels in Rabbit Cerebral Artery Myocytes.
From: University of Vermont, Department of Pharmacology, Given Bldg., 89 Beaumont Ave., Burlington, VT 05405-0068, USA.
American journal of physiology. Heart and circulatory physiology
- Publish Date: Sep 2007
- ISSN: 0363-6135
- Volume: 293
- Issue: 3
- Pages: H1750-9
- Medium: Print
- Language: English
- Citation (JAMA): Koide Masayo, Penar Paul L, Tranmer Bruce I, et al. Heparin-binding Egf-like Growth Factor Mediates Oxyhemoglobin-induced Suppression of Voltage-dependent Potassium Channels in Rabbit Cerebral Artery Myocytes.. Am. J. Physiol. Heart Circ. Physiol. Sep 2007;293:H1750-9
Abstract
Oxyhemoglobin (OxyHb) can suppress voltage-dependent K(+) channel (K(V)) currents through protein tyrosine kinase activation, which may contribute to cerebral vasospasm following subarachnoid hemorrhage. Here we have tested the hypothesis that shedding of heparin-binding EGF-like growth factor (HB-EGF) and the resulting activation of the tyrosine kinase EGF receptor (EGFR) underlie OxyHb-induced K(V) channel suppression in the cerebral vasculature. With the use of the conventional whole cell patch-clamp technique, two EGFR ligands, EGF and HB-EGF, were found to mimic OxyHb-induced K(V) suppression in rabbit cerebral artery myocytes. K(V) current suppression by OxyHb or EGF ligands was eliminated by a specific EGFR inhibitor, AG-1478, but was unaffected by PKC inhibition. Compounds (heparin and CRM-197) that specifically interfere with HB-EGF signaling eliminated OxyHb-induced K(V) suppression, suggesting that HB-EGF is the EGFR ligand involved in this pathway. HB-EGF exists as a precursor protein that, when cleaved by matrix metalloproteases (MMPs), causes EGFR activation. MMP activation was detected in OxyHb-treated arteries by gelatin zymography. Furthermore, the MMP inhibitor (GM-6001) abolished OxyHb-induced K(V) current suppression. We also observed K(V) current suppression due to EGFR activation in human cerebral artery myocytes. In conclusion, these data demonstrate that OxyHb induces MMP activation, causing HB-EGF shedding and enhanced EGFR activity, ultimately leading to K(V) channel suppression. We propose that EGFR-mediated K(V) suppression contributes to vascular pathologies, such as cerebral vasospasm, and may play a more widespread role in the regulation of regional blood flow and peripheral resistance.
Mesh Headings (Keywords): Animals, Cerebral Arteries, Epidermal Growth Factor, Intercellular Signaling Peptides and Proteins, Male, Metalloproteases, Myocytes, Smooth Muscle, Oxyhemoglobins, Patch-Clamp Techniques, Potassium Channels, Voltage-Gated, Protein Kinase C, Rabbits, Receptor, Epidermal Growth Factor, Tyrphostins
Check for Full Text / PubMed Unique Identifier (PMID): 17557914
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