Small-conductance (KCa2.1-2.3) and intermediate-conductance (KCa3.1) calcium-activated K ϩ channels are critically involved in modulating calcium-signaling cascades and membrane potential in both excitable and nonexcitable cells. Activators of these channels constitute useful pharmacological tools and potential new drugs for the treatment of ataxia, epilepsy, and hypertension. Here, we used the neuroprotectant riluzole as a template for the design of KCa2/3 channel activators that are potent enough for in vivo studies.

Atherosclerosis remains a major cause of death in the developed world despite the success of therapies that lower cholesterol and BP. The intermediate-conductance calcium-activated potassium channel KCa3.1 is expressed in multiple cell types implicated in atherogenesis, and pharmacological blockade of this channel inhibits VSMC and lymphocyte activation in rats and mice. We found that coronary vessels from patients with coronary artery disease expressed elevated levels of KCa3.1. In Apoe -/-mice, a genetic model of atherosclerosis, KCa3.1 expression was elevated in the VSMCs, macrophages, and T lymphocytes that infiltrated atherosclerotic lesions. Selective pharmacological blockade and gene silencing of KCa3.1 suppressed proliferation, migration, and oxidative stress of human VSMCs. Furthermore, VSMC proliferation and macrophage activation were reduced in KCa3.1 -/-mice. In vivo therapy with 2 KCa3.1 blockers, TRAM-34 and clotrimazole, significantly reduced the development of atherosclerosis in aortas of Apoe -/-mice by suppressing VSMC proliferation and migration into plaques, decreasing infiltration of plaques by macrophages and T lymphocytes, and reducing oxidative stress. Therapeutic concentrations of TRAM-34 in mice caused no discernible toxicity after repeated dosing and did not compromise the immune response to influenza virus. These data suggest that KCa3.1 blockers represent a promising therapeutic strategy for atherosclerosis.

Proliferation of interstitial fibroblasts is a hallmark of progressive renal fibrosis commonly resulting in chronic kidney failure. The intermediate-conductance Ca 2+ -activated K + channel (K Ca 3.1) has been proposed to promote mitogenesis in several cell types and contribute to disease states characterized by excessive proliferation. Here, we hypothesized that K Ca 3.1 activity is pivotal for renal fibroblast proliferation and that deficiency or pharmacological blockade of K Ca 3.1 suppresses development of renal fibrosis. We found that mitogenic stimulation up-regulated K Ca 3.1 in murine renal fibroblasts via a MEK-dependent mechanism and that selective blockade of K Ca 3.1 functions potently inhibited fibroblast proliferation by G 0 /G 1 arrest. Renal fibrosis induced by unilateral ureteral obstruction (UUO) in mice was paralleled by a robust up-regulation of K Ca 3.1 in affected kidneys. Mice lacking K Ca 3.1 (K Ca 3.1 −/− ) showed a significant reduction in fibrotic marker expression, chronic tubulointerstitial damage, collagen deposition and αSMA + cells in kidneys after UUO, whereas functional renal parenchyma was better preserved. Pharmacological treatment with the selective K Ca 3.1 blocker TRAM-34 similarly attenuated progression of UUO-induced renal fibrosis in wild-type mice and rats. In conclusion, our data demonstrate that K Ca 3.1 is involved in renal fibroblast proliferation and fibrogenesis and suggest that K Ca 3.1 may represent a therapeutic target for the treatment of fibrotic kidney disease.

Supplementary Figure 1 TRAM-34 treatment with 10 mg/kg initiated 2 h after reperfusion and continued for 7 days twice daily noticeably reduced infarct area following similar reductions in cerebral blood flow (control: 51.2 ± 8.2% flux reduction, n = 10; TRAM-34: 49.0 ± 7.4% flux reduction, n = 11). (A) Analysis of each affected brain slice from 2 mm to 16 mm from the frontal pole of the brain, revealed a marked reduction of TTC-defined lesion areas in all slices, which was statistically significant in the 6, 8, 10, 12 and 14-mm slices. (B) The mean infarct area was 18.8 ± 3.5% of the ipsolateral TTC + hemisphere area (n = 10) in controls and 6.6 ± 1.9% in TRAM-34 treated animals (n = 11; mean ± SEM, P = 0.007). (C) TRAM-34 treatment reduces microglia activation. Shown are means (± SEM) of ED1 + hemisphere area from the 8 and 10-mm slices from 5 animals of each group. Effects of Chronic TRAM-34 TreatmentAdult (9-11 week old) male and female rats were purchased from Charles River (Wilmington, MA) and injected i.p. for 28 days with either 20 mg/kg/d of TRAM-34 divided into two daily doses or with vehicle (n = 6 per group with 3 male and 3 female). At the end of the trial, rats were sacrificed and complete blood chemistry, hematology and necropsy performed by the Comparative Pathology Laboratory of the University of California, Davis as follows: 1. Rat were euthanized with CO 2 . 2. Whole animal weight (to mg) determined using an Ohaus analytical scale.3. Blood was collected via cardiac puncture for hematological profile (Complete blood count and differential) into EDTA coated samplette tubes. The rest of the blood will was placed in a serum separator samplette tube and separated by centrifugation at 3500 rpm. 4. The hematological profile was performed by the Comparative pathology Laboratory using a Drew Mascot 850 automated cell counter. Morphology of blood cells and WBC differential was also evaluated manually. 5. Serum Chemistry was performed on a Cobas Mira Plus chemistry analyzer. 6. Necropsies were performed and any gross lesions/changes were documented. 7. Pelage and cecal/intestinal contents was sampled and examined microscopically for parasites. 8. Liver, both kidneys, spleen, GI tract, pancreas, lung, heart, brain, bone marrow, proximal and distal lymph nodes, thymus, gonads and any lesioned organs were collected and fixed in 10% buffered formalin. Tissues were sectioned and processed to paraffin blocks. Hematoxylin and eosin stained sections from each block were examined for histologic changes by trained pathologist and any changes noted. 1) 28-Day Toxicity StudyVehicle (n = 6; 3 male, 3 female) All animals showed extra-medullary hematopoiesis in the red pulp and prominent marginal zones in the white pulp. This is a normal finding in adult rats. ‡ TRAM-34The unilateral hydronephrosis in 2 female control rats and 1 female TRAM-34 treated rat is most likely congenital in origin and has been previously seen in female rats from the same vendor. 2) 6-Months Toxicity StudyIn another trial male and female rats ...

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.

HYDROPEROXIDE LYASE (HPL) genes encode enzymes that catalyze the cleavage of fatty acid hydroperoxides into aldehydes and oxoacids. There are three HPLs in rice (Oryza sativa), designated OsHPL1 through OsHPL3. To explore the possibility of differential functional activities among these genes, we have examined their expression patterns and biochemical properties of their encoded products. Transcript analysis indicates that these genes have distinct patterns and levels of expression. OsHPL1 is ubiquitously expressed, OsHPL2 is expressed in the leaves and leaf sheaths, whereas OsHPL3 is wound inducible and expressed exclusively in leaves. OsHPLs also differ in their substrate preference as determined by in vitro enzyme assays using 9-/13-hydroperoxy linolenic and 9-/13-hydroperoxy linoleic acids as substrates. OsHPL1 and OsHPL2 metabolize 9-/13-hydroperoxides, whereas OsHPL3 metabolizes 13-hydroperoxy linolenic acid exclusively. Sequence alignments of the HPL enzymes have identified signature residues potentially responsible for the substrate specificity/preference of these enzymes. All three OsHPLs are chloroplast localized as determined by chloroplast import assays and green fluorescent protein (GFP) fusion studies. Aldehyde measurements in transgenic Arabidopsis (Arabidopsis thaliana) plants overexpressing individual OsHPL-GFP fusions indicate that all rice HPLs are functional in a heterologous system, and each of them generates a distinct signature of the metabolites. Interestingly, these aldehydes were only detectable in leaves, but not in roots, despite similar levels of OsHPL-GFP proteins in both tissues. Similarly, there were undetectable levels of aldehydes in rice roots, in spite of the presence of OsHPL1 transcripts. Together, these data suggest that additional tissue-specific mechanism(s) beyond transcript and HPL enzyme abundance, regulate the levels of HPL-derived metabolites.

Exposure to airborne particles is associated with increased cardiovascular morbidity and mortality. During the combustion of chlorine-containing hazardous materials and fuels, chlorinated hydrocarbons chemisorb to the surface of transition metal-oxide-containing particles, reduce the metal, and form an organic free radical. These radical-particle systems can survive in the environment for days and are called environmentally persistent free radicals (EPFRs). This study determined whether EPFRs could decrease left ventricular function before and after ischemia and reperfusion (I/R) in vivo. Male Brown Norway rats were dosed (8 mg/kg, i.t.) 24 hr prior to testing with particles containing the EPFR of 1, 2-dichlorobenzene (DCB230). DCB230 treatment decreased systolic and diastolic function. DCB230 also produced pulmonary and cardiac inflammation. After ischemia, systolic, but not diastolic function was significantly decreased in DCB230-treated rats. Ventricular function was not affected by I/R in control rats. There was greater oxidative stress in the heart and increased 8-isoprostane (biomarker of oxidative stress) in the plasma of treated vs control rats after I/R. These data demonstrate for the first time that DCB230 can produce inflammation and significantly decrease cardiac function at baseline and after I/R in vivo. Furthermore, these data suggest that EPFRs may be a risk factor for cardiac toxicity in healthy individuals and individuals with ischemic heart disease. Potential mechanisms involving cytokines/chemokines and/or oxidative stress are discussed.

The small molecule PAP-1 (5-(4-phenoxybutoxy)psoralen) is a selective blocker of the voltage-gated potassium channel Kv1.3 that is highly expressed in cell membranes of activated effector memory T-cells (TEM). The blockade of Kv1.3 results in membrane depolarization and inhibition of TEM cell proliferation and function. In this study, the in vitro effects of PAP-1 on rhesus macaques (RM) T cells and the in vivo toxicity and pharmacokinetics (PK) were examined in RM with the ultimate aim of utilizing PAP-1 to define the role of TEM in RM infected with simian immunodeficiency virus (SIV). Electrophysiological studies on RM T-cells revealed a Kv1.3 expression pattern similar to that in human T-cells. Thus, PAP-1 effectively suppressed RM TEM cell proliferation. Intravenously administered PAP-1 showed a half-life of 6.4 hrs and the volume of distribution suggested that it is distributed extensively into extravascular compartments. Orally administered PAP-1 was efficiently absorbed and plasma concentrations in RM undergoing a 30-day chronic dosing study indicated that PAP-1 levels that are suppressive to TEM cells in vitro can be achieved and maintained in vivo at a non-toxic dose. PAP-1 selectively inhibited TEM function in vivo as indicated by a modest reactivation of cytomegalovirus (CMV) replication. Immunization of these chronically-treated RM with the live influenza A/PR8 virus suggest that the development of an in vivo flu-specific central memory response was unaffected by PAP-1. These RM remained diseasefree during the entire course of the PAP-1 study. Collectively these data provide a rational basis for future studies with PAP-1 in SIV-infected RM.