ABSTRACT
INTRODUCTION: K(+) channels are central to vascular pathophysiology. Previous results demonstrated that phenotypic modulation associates with a change in Kv1.3 to Kv1.5 expression, and that Kv1.3 blockade inhibits proliferation of VSMCs cultures. PURPOSE: To explore whether the Kv1.3 to Kv1.5 switch could be a marker of the increased risk of intimal hyperplasia in essential hypertension and whether systemic treatment with Kv1.3 blockers can prevent intimal hyperplasia after endoluminal lesion . METHODS: Morphometric and immunohistochemical analysis were performed in arterial segments following arterial injury and constant infusion of the Kv1.3 blocker PAP-1 during 28 days. Differential expression of K(+) channel genes was studied in VSMC from hypertensive (BPH) and normotensive (BPN) mice, both in control and after endoluminal lesion. Finally, the migration and proliferation rate of BPN and BPH VSMCs was explored in vitro. RESULTS: Changes in mRNA expression led to an increased Kv1.3/Kv1.5 ratio in BPH VSMC. Consistent with this, arterial injury in BPH mice induced a higher degree of luminal stenosis, (84 ± 4% vs. 70 ± 5% in BPN, p < 0.01), although no differences in migration and proliferation rate were observed in cultured VSMCs. The in vivo proliferative lesions were significantly decreased upon PAP-1 systemic infusion (18 ± 6% vs. 58 ± 20% with vehicle, p < 0.05). CONCLUSIONS: Hypertension leads to a higher degree of luminal stenosis in our arterial injury model, that correlates with a decreased expression of Kv1.5 channels. Kv1.3 blockers decreased in vitro VSMCs proliferation, migration, and in vivo intimal hyperplasia formation, pointing to Kv1.3 channels as promising therapeutical targets against restenosis.
Subject(s)
Arteries/drug effects , Hyperplasia/metabolism , Hypertension/metabolism , Kv1.3 Potassium Channel/antagonists & inhibitors , Kv1.3 Potassium Channel/metabolism , Potassium Channel Blockers/pharmacology , Tunica Intima/drug effects , Animals , Arteries/metabolism , Cell Movement/drug effects , Cell Proliferation/drug effects , Cells, Cultured , Endothelium, Vascular/drug effects , Endothelium, Vascular/metabolism , Essential Hypertension , Female , Hyperplasia/drug therapy , Hypertension/drug therapy , Male , Mice , Muscle, Smooth, Vascular/drug effects , Muscle, Smooth, Vascular/metabolism , Pancreatitis-Associated Proteins , Tunica Intima/metabolismABSTRACT
Moderately halophilic bacteria are microorganisms that grow optimally in media containing 3%-15% (w/v) salt. They are represented by a heterogeneous group of microorganisms included in many different genera. Gram-negative moderately halophilic bacteria have been studied in more detail, but studies on gram-positive species are more scarce. Recent studies carried out by our research group on gram-positive moderate halophiles have permitted clarifying their taxonomic and phylogenetic position and describing new species. Thus, we have isolated six strains from ponds of salterns that show phenotypic and genotypic characteristics similar to those of Nesterenkonia halobia (formerly Micrococcus halobius), a moderately halophilic gram-positive coccus that was described on the basis of a single strain. Our data demonstrate quite clearly that they are members of this species and contribute to a better description of these moderately halophilic cocci. Similarly, a study of a large number of gram-positive moderately halophilic rods that were able to produce endospores led us to describe a new species, designated Bacillus salexigens. Further, isolates grouped in other three phenons, obtained by numerical taxonomy analysis and showing phenotypic features quite similar to those of this species, represent different genomovars, with very low DNA-DNA homology. Although they might represent additional new species, it will be necessary to determine new phenotypic features to differentiate them from previously described Bacillus species. We have also studied the viability of some old enrichments provided by B.E. Volcani, which were set up in 1936. We isolated 31 gram-positive motile endospore-forming rods that, according to their phenotypic characteristics, could represent a new species of the genus Bacillus.
Subject(s)
Bacillus/classification , Bacillus/genetics , Halobacteriaceae/classification , Halobacteriaceae/genetics , Bacillus/growth & development , DNA, Archaeal/chemistry , DNA, Archaeal/genetics , DNA, Bacterial/chemistry , DNA, Bacterial/genetics , Environment , Fresh Water/microbiology , Halobacteriaceae/growth & development , Phenotype , Sodium ChlorideABSTRACT
Bacillus salexigens sp. nov. is proposed based on the characteristics of six moderately halophilic, grampositive, rod-shaped strains isolated from salterns and hypersaline soils located in different geographical areas of Spain. These strains were motile, formed endospores, were strictly aerobic, were catalase and oxidase positive, and contained peptidoglycan of the meso-diamlnopimelic acid type in their vegetative cell walls. The DNA base compositions of these strains ranged from 36.3 to 39.5 mol%, and these organisms constitute a homology group with levels of DNA-DNA homology ranging from 73 to 100%. The 16S rRNA sequence of strain C-20MoT, which was used as the representative strain of these isolates, groups with the 16S rRNA sequences of members of the genus Bacillus, and the highest level of similarity is 95.4%. The type strain is strain C-20Mo (= ATCC 700290 = DSM 11483 = CCM 4646).
