Local delivery of the KCa3.1 blocker, TRAM-34, prevents acute angioplasty-induced coronary smooth muscle phenotypic modulation and limits stenosis.
OBJECTIVE
We previously demonstrated that upregulation of intermediate-conductance Ca(2+)-activated K(+) channels (K(Ca)3.1) is necessary for mitogen-induced phenotypic modulation in isolated porcine coronary smooth muscle cells (SMCs). The objective of the present study was to determine the role of K(Ca)3.1 in the regulation of coronary SMC phenotypic modulation in vivo using a swine model of postangioplasty restenosis.


RESULTS
Balloon angioplasty was performed on coronary arteries of swine using either noncoated or balloons coated with the specific K(Ca)3.1 blocker TRAM-34. Expression of K(Ca)3.1, c-jun, c-fos, repressor element-1 silencing transcription factor (REST), smooth muscle myosin heavy chain (SMMHC), and myocardin was measured using qRT-PCR in isolated medial cells 2 hours and 2 days postangioplasty. K(Ca)3.1, c-jun, and c-fos mRNA levels were increased 2 hours postangioplasty, whereas REST expression decreased. SMMHC expression was unchanged at 2 hours, but decreased 2 days postangioplasty. Use of TRAM-34 coated balloons prevented K(Ca)3.1 upregulation and REST downregulation at 2 hours, SMMHC and myocardin downregulation at 2 days, and attenuated subsequent restenosis 14 and 28 days postangioplasty. Immunohistochemical analysis demonstrated corresponding changes at the protein level.


CONCLUSIONS
Blockade of K(Ca)3.1 by delivery of TRAM-34 via balloon catheter prevented smooth muscle phenotypic modulation and limited subsequent restenosis.
Tharp
D L
DL
Department of Biomedical Sciences, University of Missouri, Columbia, MO 65211, USA.
Wamhoff
B R
BR
Wulff
H
H
Raman
G
G
Cheong
A
A
Bowles
D K
DK
D015906:Angioplasty, Balloon, Coronary / Q000009:adverse effects; D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects; D023921:Coronary Stenosis / Q000473:pathology / Q000517:prevention & control*; D003331:Coronary Vessels / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D004195:Disease Models, Animal; D051660:Intermediate-Conductance Calcium-Activated Potassium Channels / Q000037:antagonists & inhibitors* / Q000378:metabolism; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D010641:Phenotype; D026902:Potassium Channel Blockers / Q000494:pharmacology*; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism; D016755:Proto-Oncogene Proteins c-jun / Q000378:metabolism; D011720:Pyrazoles / Q000494:pharmacology*; D013552:Swine; D014157:Transcription Factors / Q000378:metabolism
D051660:Intermediate-Conductance Calcium-Activated Potassium Channels; D026902:Potassium Channel Blockers; D016760:Proto-Oncogene Proteins c-fos; D016755:Proto-Oncogene Proteins c-jun; D011720:Pyrazoles; C411671:TRAM 34; D014157:Transcription Factors