Faculty Collaboration Database

Colonic inflammation alters Src kinase-dependent gating properties of single Ca2+ channels via tyrosine nitration. Am J Physiol Gastrointest Liver Physiol 2010 Jun;298(6):G976-84

Date

04/10/2010

Pubmed ID

20378833

Pubmed Central ID

PMC3061627

DOI

10.1152/ajpgi.00056.2010

Scopus ID

2-s2.0-77952717910 (requires institutional sign-in at Scopus site)   13 Citations

Abstract

Nitration of L-type calcium channels during colonic inflammation impairs phosphorylation by the tyrosine kinase, Src kinase. This results in decreased calcium currents. The purpose of this study was to determine the mechanism of the downregulation of Ca2+ currents in colonic inflammation. In whole cell voltage clamp of mouse single smooth muscle cells, long-duration depolarization produced noninactivating calcium currents that were significantly reduced by the Src kinase inhibitor, protein phosphatase 2 (PP2). Unitary Ba2+ currents were recorded upon repolarization from positive potentials in cell-attached patches of smooth muscle and hCa(v)1.2b-transfected cells to assess the properties of the single channels attributed to the noninactivating open state. Repolarization to -40 mV from 0 mV resulted in single-channel events with conductance of approximately 23 pS. The ensemble average of the tail currents from 1,000 sweeps was 337 +/- 27 fA in control and 218 +/- 49 fA (P < 0.05) in inflamed cells. Neither open-probability nor open-time constants were significantly different between control and inflamed cells. However, the transition to the open state measured as channel availability was significantly reduced from 19 +/- 3% to 6.4 +/- 1%. Similarly, peak ensemble average current and channel availability were significantly reduced by PP2 and treatment with peroxynitrite in control cells. Mutation of COOH-terminal tyrosine residues in hCa(v)1.2b Chinese hamster ovarian cells also decreased peak ensemble average tail currents and availability. The present findings suggest that the transition of Ca2+ channels to the noninactivating open state is Src kinase dependent. Tyrosine nitration prevents Src-mediated transitions, leading to decreased calcium currents.

Author List

Ross GR, Kang M, Akbarali HI

Author

Gracious R. Ross Research Scientist II in the Cardiovascular Center department at Medical College of Wisconsin

MESH terms used to index this publication - Major topics in bold

Animals
CHO Cells
Calcium Channels
Colitis
Cricetinae
Cricetulus
Ion Channel Gating
Male
Mice
Tyrosine
src-Family Kinases