Effects of Losartan on Catecholamine Release in the Isolated Rat Adrenal Gland

The aim of this study was to determine whether losartan, an angiotensin II (Ang II) type 1 (AT1) receptor could influence the CA release from the isolated perfused model of the rat adrenal medulla. Losartan (5~50 micrometer) perfused into an adrenal vein for 90 min produced dose- and time-dependent inhibition of the CA secretory responses evoked by ACh (5.32 mM), high K+ (56 mM, a direct membrane depolarizer), DMPP (100 micrometer) and McN-A-343 (100 micrometer). Losartan failed to affect basal CA output. Furthermore, in adrenal glands loaded with losartan (15 micrometer) for 90 min, the CA secretory responses evoked by Bay-K-8644 (10 micrometer, an activator of L-type Ca2+ channels), cyclopiazonic acid (10 micrometer, an inhibitor of cytoplasmic Ca2+-ATPase), veratridine (100 micrometer, an activator of Na+ channels), and Ang II (100 nM) were markedly inhibited. However, at high concentrations (150~300 micrometer), losartan rather enhanced the CA secretion evoked by ACh. Collectively, these experimental results suggest that losartan at low concentrations inhibits the CA secretion evoked by cholinergic stimulation (both nicotininc and muscarinic receptors) as well as by membrane depolarization from the rat adrenal medulla, but at high concentration it rather inhibits ACh-evoked CA secretion. It seems that losartan has a dual action, acting as both agonist and antagonist to nicotinic receptors of the rat adrenal medulla, which might be dependent on the concentration. It is also thought that this inhibitory effect of losartan may be mediated by blocking the influx of both Na+ and Ca2+ into the rat adrenomedullary chromaffin cells as well as by inhibiting the Ca2+ release from the cytoplasmic calcium store, which is thought to be relevant to the AT1 receptor blockade, in addition to its enhancement of the CA release.

Expression of Toll-like Receptor 4 on Human Keratinocytes by Lipoteichoic Acid / 대한피부과학회지

BACKGROUND: We have recently shown that lipopolysaccharide (LPS), a major biologically active component of Gram-negative bacteria, mediate the activation of human keratinocytes by CD14 and Toll-like receptor (TLR 4). However, the mechanism of activation of keratinocytes by Gram-positive bacterial toxins remains unclear. OBJECTIVE: We investigated the mechanism of activation of human keratinocytes by lipoteichoic acid (LTA), a main stimulatory component of Gram-positive bacteria. METHODS: The effects of LTA on CD14, TLR2 and TLR4 mRNA expression were measured by quantitative RT-PCR in cultured human keratinocytes. To determine whether the effects of LTA on CD14, TLR2 and TLR4 expressions of the human keratinocytes were biologically functional, NF-kappaB nuclear translocation and IL-1alpha secretion were measured by immunofluorescence staining and ELISA, respectively. Furthermore, to determine whether these effects by LTA were specific for CD14, TLR2 and TLR4, some cells were pretreated with anti-CD14, anti-TLR2, or anti-TLR2 monoclonal antibodies prior to the addition of LTA. RESULTS: TLR4 mRNA expression on keratinocytes was augmented by exposure to LTA. LTA binding to keratinocytes resulted in NF-kappaB nuclear translocation and secretion of interleukin-1alpha. These responses by LTA were effectively abrogated by preincubating cells with anti-TLR4 monoclonal antibody, but not with anti-CD14 or anti- TLR2 monoclonal antibodies. CONCLUSION: These results indicate that, similar to LPS, LTA induces activation of human keratinocytes mainly through TLR4, however, in contrast to LPS signaling, LTA-induced keratinocyte activation is CD14-independent.

Microdeletion of Chromosome 7 in Williams Syndrome and Supravalvular Aortic Stenosis

PURPOSE: Williams syndrome is characterized by supravalvular aortic stenosis, mental retardation and peculiar facial appearance. Its genetic etiology is considered to be a hemizygotic deletion in Chromosome 7q11.23, which includes the elastin gene. We examined the hemizygotic deletion of Chromosome 7q11.23 in 12 Korean Williams syndrome patients and 8 patients with isolated supravalvular aortic stenosis and performed deletion mapping in the Williams syndrome patients. METHODS: Hemizygotic deletion was determined with fluorescence in situ hybridization(FISH) using the bacterial artificial chromosome clone 244H3, which has the genomic DNA sequence of elastin gene, as a probe. For the deletion mapping, polymorphism analysis of 10 Williams syndrome patients and their parents was done with 9 dinucleotide repeat sequence polymorphic markers(D7S499, D7S672, D7S653, ELN, D7S2472, D7S1870, D7S2518, D7S675 and D7S669). RESULTS: In the Williams syndrome patients, FISH showed deletion in all. In patients with isolated supravalvular aortic stenosis, FISH showed deletion in one, partial deletion in another and no deletion in the other six patients. Polymorphism analysis showed that alleles at three loci(ELN, D7S2472 and D7S1870) were commonly deleted in the Williams syndrome patients. Paternal alleles were deleted in six patients and maternal alleles were deleted in four. CONCLUSION: Hemizygotic deletion could be detected in Williams syndrome patients with FISH and the commonly deleted loci were ELN, D7S2472 and D7S1870. Most patients with isolated supravalvular aortic stenosis showed no deletion with FISH and the genetic defect should be much smaller than what FISH could detect.

Microdeletion of Chromosome 7 in Williams Syndrome and Supravalvular Aortic Stenosis

PURPOSE: Williams syndrome is characterized by supravalvular aortic stenosis, mental retardation and peculiar facial appearance. Its genetic etiology is considered to be a hemizygotic deletion in Chromosome 7q11.23, which includes the elastin gene. We examined the hemizygotic deletion of Chromosome 7q11.23 in 12 Korean Williams syndrome patients and 8 patients with isolated supravalvular aortic stenosis and performed deletion mapping in the Williams syndrome patients. METHODS: Hemizygotic deletion was determined with fluorescence in situ hybridization(FISH) using the bacterial artificial chromosome clone 244H3, which has the genomic DNA sequence of elastin gene, as a probe. For the deletion mapping, polymorphism analysis of 10 Williams syndrome patients and their parents was done with 9 dinucleotide repeat sequence polymorphic markers(D7S499, D7S672, D7S653, ELN, D7S2472, D7S1870, D7S2518, D7S675 and D7S669). RESULTS: In the Williams syndrome patients, FISH showed deletion in all. In patients with isolated supravalvular aortic stenosis, FISH showed deletion in one, partial deletion in another and no deletion in the other six patients. Polymorphism analysis showed that alleles at three loci(ELN, D7S2472 and D7S1870) were commonly deleted in the Williams syndrome patients. Paternal alleles were deleted in six patients and maternal alleles were deleted in four. CONCLUSION: Hemizygotic deletion could be detected in Williams syndrome patients with FISH and the commonly deleted loci were ELN, D7S2472 and D7S1870. Most patients with isolated supravalvular aortic stenosis showed no deletion with FISH and the genetic defect should be much smaller than what FISH could detect.