Local Delivery of the K _Ca 3.1 Blocker, TRAM-34, Prevents Acute Angioplasty-Induced Coronary Smooth Muscle Phenotypic Modulation and Limits Stenosis

Abstract

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. Methods and 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. Conclusion— Blockade of K Ca 3.1 by delivery of TRAM-34 via balloon catheter prevented smooth muscle phenotypic modulation and limited subsequent restenosis.

Renal fibrosis is attenuated by targeted disruption of K Ca 3.1 potassium channels

“…Thus, the results from both studies, using either a genetic or a pharmacological approach, corroborate the proposed concept that K Ca 3.1 channels play an important role in the pathogenesis of renal fibrosis. Of note, in animal models of acute vascular injury (17,19), atherosclerosis (26), angiogenesis (15), and endometrial cancer (27), administration of selective K Ca 3.1 blockers has been shown to also prevent excessive cell proliferation in vivo and ameliorate the course of disease. Importantly, long-term treatment with TRAM-34 at therapeutic concentrations caused no discernible toxicity and did not compromise immune responses in mice and rats (17,26), which is in line with observations of the present study.…”

“…Conversely, we and others have recently demonstrated in models of experimental angiogenesis (15), post-interventional arterial restenosis (17,19), atherosclerosis (26), and endometrial cancer (27), that selective pharmacological inhibition or knockdown of K Ca 3.1 suppresses mitogen-driven cell proliferation and ameliorates disease progression. Thus, K Ca 3.1 could have a pivotal role in disease states characterized by excessive cell proliferation and may emerge as a promising pharmacotherapeutic target for antiproliferative treatment.…”

“…Whereas the first directly mediate Ca 2ϩ inflow, the latter regulate membrane potential and thus provide the driving force for Ca 2ϩ entry (13). In particular, the intermediate-conductance K Ca (K Ca 3.1) has been shown to play an important role in promoting mitogenesis in several tissues such as the endothelium (15,16), vascular smooth muscle (17)(18)(19), and T lymphocytes (20) as well as in several cell lines including A7r5 neonatal aortic smooth muscle cells (21), 10T1/2-MRF4 myogenic fibroblasts (22,23), HMEC-1 dermal endothelial cells (15), and some cancer cell lines (24,25).…”

The Smooth Muscle Cell-restricted KCNMB1 Ion Channel Subunit Is a Direct Transcriptional Target of Serum Response Factor and Myocardin

“…Injured arteries and control uninjured arteries were rapidly dissected for total RNA extraction. Balloon angioplasty (1.4ϫ overinflation) was performed on the left circumflex and left anterior descending coronary arteries of castrated male swine as described (27). Coronary arteries were harvested at 2 h and 2 days following balloon catheter injury and quickly frozen in liquid nitrogen.…”

Calcium-Activated Potassium Channel KCa3.1 in Lung Dendritic Cell Migration

“…Functionally, KCa3.1 plays a key role in calcium-dependent cell functions, such as proliferation, activation, and migration, in a broad range of cell types. KCa3.1 regulates the proliferation of T lymphocytes (17), transformed cells (18), airway and vascular smooth muscle cells (12,(19)(20)(21)(22), and vascular endothelial cells (23). The selective blockade of KCa3.1 largely inhibits endothelial cell proliferation, suggesting that KCa3.1 is a potential target for angiogenesis disorders (23).…”