Simultaneous detection of barrier- and immune-related gene variations in patients with atopic dermatitis by reverse blot hybridization assay.

BACKGROUND: Hereditary factors are involved in the pathogenesis of atopic dermatitis (AD). However, AD-related gene variations are significantly different across ethnicities. AIM: To identify mutations and single-nucleotide polymorphisms (SNPs) in barrier- or immune-related genes from Korean patients with AD and compare the variations with those observed in nonatopic healthy controls (HCs), and to use novel reverse blot hybridization assay (REBA) for AD-related gene variants. METHODS: We carried out REBA to simultaneously detect variations in genes related to barrier or immune function, namely, FLG, SPINK5, KLK7, DEFB1, TNFα, KDR, FCER1A, IL4, IL5,IL5RA, IL9, IL10, IL12, IL12R, IL13 and IL18, from Korean patients with AD, and compared the variation to that in nonatopic healthy controls. RESULTS: The homozygous mutants of KLK7 and SPINK5-2475, and the heterozygous mutants of FLG 3321delA, SPINK5-1156, DEFB1, KDR, IL5RA, IL9 and IL12RB1 were significantly more frequent in AD. It has been predicted that the larger the number of gene variants, the higher the odds ratio of AD prevalence; however, we did not find any significant correlation between the number of gene variants and AD severity. CONCLUSION: Using REBA, we identified more genetic variants that can predict AD occurrence. We also verified that REBA can be used to easily and accurately detect multiple AD-related gene variants simultaneously. In addition, we identified a correlation between KLK7 mutation and AD in Koreans, which is the first such report, to our knowledge.

HIV-associated neurocognitive disorder in HIV-infected Koreans: the Korean NeuroAIDS Project.

OBJECTIVES: HIV-associated neurocognitive disorder (HAND) is an independent predictor of early mortality and is associated with many difficulties in activities of daily living. We sought to determine the prevalence of and risk factors for HAND in HIV-infected Koreans. In addition, we investigated the performance of screening tools and components of neuropsychological (NP) tests for diagnosing HAND. METHODS: HIV-infected patients were enrolled consecutively from two different urban teaching hospitals in Seoul, South Korea between March 2012 and September 2012. Participants completed a detailed NP assessment of six cognitive domains commonly affected by HIV. The Frascati criteria were used for diagnosing HAND. Four key questions, the International HIV Dementia Scale (IHDS) and Montreal Cognitive Assessment (MoCA)-K were also assessed as potential tools for screening for HAND. RESULTS: Among the 194 participants, the prevalence of HAND was 26.3%. Asymptomatic neurocognitive impairment and minor neurocognitive disorder accounted for 52.9 and 47.1% of the patients with HAND, respectively. In multivariate analysis, haemoglobin (Hb) level ≤ 13 g/dL (P = 0.046) and current use of a protease inhibitor-based regimen (P = 0.031) were independent risk factors for HAND. The sensitivity and specificity of the IHDS were 72.6 and 60.8%, and those of MoCA-K were 52.9 and 73.4%, respectively. The IHDS (P < 0.001) and MoCA-K (P < 0.001) were both useful for screening for HAND. Among NP tests, the sensitivity and specificity of the Grooved Pegboard Test were 90.2 and 72.0%, and those of the Wisconsin Card Sorting Test were 61.2 and 84.4%, respectively. CONCLUSIONS: HAND is a prevalent comorbidity in HIV-infected Koreans. Active screening and diagnosis with effective tools, such as the IHDS, MoCA-K and Grooved Pegboard Test, could be used to identify this important complication.

Recapitulation of genome-wide association studies on body mass index in the Korean population.

Obesity is a risk factor for multiple disorders such as diabetes and cardiovascular disease. Recently, a genome-wide association study for body mass index (BMI) was conducted in 249 796 individuals of European ancestry by the Genetic Investigation of Anthropometric Traits (GIANT) consortium. They identified 14 known obesity susceptibility loci and 18 new loci associated with BMI at the genome-wide significance level (P<5 × 10⁻8). Because the prevalence and severity of obesity vary among ethnic groups, it is worthy to investigate these results in another ethnic population. We examined the BMI association of 19 single-nucleotide polymorphisms (SNPs) out of the 32 in 8842 individuals from the Korean Association Resource data, and found 12 SNPs to be associated with BMI in the Korean population. Eight loci, rs10968576 (BDNF), rs3817334 (MTCH2), rs1558902 (FTO), rs571312 (MC4R), rs543874 (SEC16B), rs987237 (TFAP2B), rs2867125 (TMEM18) and rs7138803 (FAIM2), were previously known obesity susceptibility loci, and the remaining four loci, rs1514175 (TNNI3K), rs206936 (NUDT3), rs4771122 (MTIF3) and rs2241423 (MAP2K5), were newly identified as BMI loci by the GIANT study. Further, all 12 SNPs showed the same direction of effect on BMI between the two ethnic groups, suggesting a similar genetic architecture governing the obesity.

Carbapenem-resistant Acinetobacter baumannii: diversity of resistant mechanisms and risk factors for infection.

Carbapenem-resistant Acinetobacter baumannii (CRAB) are an increasing infectious threat in hospitals. We investigated the clinical epidemiology of CRAB infections vs. colonization in patients, and examined the mechanisms of resistance associated with elevated minimum inhibitory concentrations (MICs) for carbapenems. From January to June 2009, 75 CRAB strains were collected. CRAB infection was significantly associated with malignancy and a high APACHE II score. The most dominant resistance mechanism was ISAba1 preceding OXA-51, producing strains with overexpression of efflux pump. Strains carrying blaOXA-23-like enzymes had higher carbapenem MICs than those carrying blaOXA-51-like enzymes; however, the presence of multiple mechanisms did not result in increased resistance to carbapenems. There was no difference in the resistance mechanisms in strains from infected and colonized patients. The majority of strains were genetically diverse by DNA macrorestriction although there was evidence of clonal spread of four clusters of strains in patients.

Diagnostic value of 18F-FDG PET/CT in patients with fever of unknown origin.

This study investigates the diagnostic value of (18) F-fluorodeoxyglucose positron emission tomography/computed tomography ((18) F-FDG PET/CT) in patients with 109 classical fever of unknown origin (FUO). Of the 48 (18) F-FDG PET/CT scans, 41 (85.4%) were interpreted as abnormal, and 25 (52.1% of all scans) were considered clinically helpful. The final cause of fever was determined in 41 patients (85.4%); infection (25%), malignancy (12.5%), non-infectious inflammatory disease (16.7%) and miscellaneous causes (31.3%). (18) F-FDG PET/CT contributed to the final diagnosis of FUO in 65.8%.

Acute cytomegalovirus pneumonia and hepatitis presenting during acute HIV retroviral syndrome.

Cytomegalovirus (CMV) disease is a frequent opportunistic infection that usually occurs in the late stages of HIV infection as a result of reactivation of a latent infection. We report a case of a 23-year-old man with acute retroviral syndrome complicated by coexisting CMV pneumonia and CMV hepatitis, which were documented by histopathological examination. His CMV pneumonia and hepatitis were assumed to be primary CMV diseases owing to the absence of CMV IgG antibody. To the best of our knowledge, this is the first case of simultaneous CMV pneumonia and hepatitis occurring as primary CMV diseases during primary HIV infection. This case indicates that invasive CMV diseases such as pneumonia and hepatitis should be considered even in patients with primary HIV infection.

Effects of subinhibitory concentrations of chlorhexidine and mupirocin on biofilm formation in clinical meticillin-resistant Staphylococcus aureus.

BACKGROUND: The effects of subinhibitory concentrations (sub-MICs) of antibacterial agents on the biofilm-forming ability of Staphylococcus aureus require further study. AIM: To investigate the effects of sub-MICs of chlorhexidine and mupirocin on biofilm formation in clinical meticillin-resistant Staphylococcus aureus (MRSA) isolates. METHODS: MRSA isolates were collected from patients with bloodstream infections at a tertiary care hospital. The basal level of biofilm formation and biofilm induction by sub-MICs of chlorhexidine and mupirocin were evaluated by measuring biofilm mass stained with Crystal Violet. FINDINGS: Of the 112 MRSA isolates tested, 63 (56.3%) and 44 (39.3%) belonged to sequence type (ST)5 and ST72 lineages, respectively, which are the predominant healthcare- and community-associated clones in South Korea. ST5 isolates were more likely to have chlorhexidine MIC ≥4 (73.0% vs 29.5%), resistance to mupirocin (23.8% vs 0%), agr dysfunction (73.0% vs 9.1%), and qacA/B gene (58.7% vs 2.3%) compared to ST72 isolates. The basal level of biofilm formation ability was frequently stronger in ST72 isolates compared to ST5 isolates (77.3% vs 12.7%). Sub-MICs of chlorhexidine and mupirocin promoted biofilm formation in 56.3% and 53.6%, respectively, of all isolates. Biofilm induction was more prevalent in ST5 isolates (85.7% for chlorhexidine, 69.8% for mupirocin) than in ST72 isolates (15.9% for chlorhexidine, 27.3% for mupirocin). CONCLUSION: Sub-MICs of chlorhexidine and mupirocin promoted biofilm formation in half of the clinical MRSA isolates. Our results suggest that ST5 MRSA biofilm can be induced together with some other bacterial virulent factors following exposure to chlorhexidine, which might confer a survival advantage to this clone in the healthcare environment.

Total serum bilirubin and 8-year incident type 2 diabetes mellitus: The Korean Genome and Epidemiology Study.

AIM: In this study, the impact of serum bilirubin on new-onset type 2 diabetes mellitus (T2DM) in Korean adults was investigated. METHODS: Data were obtained from the Korean Genome and Epidemiology Study (KoGES), a population-based prospective cohort study. The study enrolled 8650 adults (4015 men and 4635 women), aged 40 to 69 years, who underwent a mean follow-up of 8.4 years. The study population was divided into quartiles (Q) of serum bilirubin levels, with cut-off points at 0.46, 0.61 and 0.82mg/dL for men, and 0.35, 0.47 and 0.61mg/dL for women. T2DM was defined based on the following data: fasting blood glucose≥7.0mmol/L, HbA1c level≥6.5% or 2-h plasma glucose≥11.1mmol/L during a 75-g oral glucose tolerance test. RESULTS: Over the mean 8.4-year follow-up, 786 participants (9.1%) developed T2DM. Compared with Q1, the odds ratios (ORs) and 95% confidence intervals (CIs) for T2DM incidence were 0.52 (0.36-0.74) in men and 0.56 (0.38-0.83) in women aged ≥50 years, respectively, in the highest Q group after adjusting for possible confounding factors. These significant results persisted in those with impaired glucose tolerance and impaired fasting glucose. CONCLUSION: The results of this study reveal a protective role for serum total bilirubin on new-onset T2DM in Korean men and women. In addition, serum total bilirubin had favourable effects on new-onset T2DM in those with impaired glucose tolerance and impaired fasting glucose.

Identification of OAT1/OAT3 as Contributors to Cisplatin Toxicity.

Cisplatin is among the most widely used anticancer drugs and known to cause a dose-limiting nephrotoxicity, which is partially dependent on the renal uptake carrier OCT2. We here report a previously unrecognized, OCT2-independent pathway of cisplatin-induced renal injury that is mediated by the organic anion transporters OAT1 and OAT3. Using transporter-deficient mouse models, we found that this mechanism regulates renal uptake of a mercapturic acid metabolite of cisplatin that acts as a precursor of a potent nephrotoxin. The function of these two transport systems can be simultaneously inhibited by the tyrosine kinase inhibitor nilotinib through noncompetitive mechanisms, without compromising the anticancer properties of cisplatin. Collectively, our findings reveal a novel pathway that explains the fundamental basis of cisplatin-induced nephrotoxicity, with potential implications for its therapeutic management.

Effect of omega-conotoxin GVIA and omega-agatoxin IVA on the capsaicin-sensitive calcitonin gene-related peptide release and autoregulatory vasodilation in rat pial arteries.

This study assesses the effect of neuronal voltage-sensitive Ca2+ channel blockers, omega-conotoxin GVIA (CTX), and omega-agatoxin IVA (AgTX) on the vasodilation and release of calcitonin gene-related peptide (CGRP), both of which were induced by either application of capsaicin or acute stepwise hypotension. Changes in pial arterial diameter were determined directly through a closed cranial window. The vasodilation of pial artery induced by either CGRP (0.1 micromol/L) or capsaicin (0.3 micromol/L) was significantly inhibited by CGRP(8-37) (0.1 micromol/L) (P < 0.05 and P < 0.05, respectively). The autoregulatory vasodilation to acute stepwise hypotension was severely attenuated by pretreatment with either CTX or AgTX. When the hypotension was kept for 2, 4, and 10 minutes, the releasable CGRP-like immunoreactivity (CGRP-LI) level (vehicle, 13.4+/-1.5 fmol/mm2/30 min) by 10 micromol/L capsaicin from the isolated pial arteries was significantly reduced in the 4- and 10-minute hypotension groups (11.3+/-1.2 fmol/mm2/30 min, P < 0.05, and 11.1+/-1.5 fmol/mm2/30 min, P < 0.05, respectively), but not in 2-min group. Moreover, the CGRP-LI level released by 10 micromol/L capsaicin (13.7+/-0.9 fmol/mm2/30 min) also was significantly depressed by pretreatment with 1 micromol/L CTX to 10.4+/-1.0 fmol/mm2/30 min (P < 0.01) and with 0.1 micromol/L AgTX to 8.7(1.7 fmol/mm2/30 min (P < 0.001), as well as by pretreatment with 10 micro-mol/L capsaicin (6.0+/-1.6 fmol/ mm2/30 min, P < 0.001). These results suggest that the neuronal N- and P-type voltage-sensitive Ca2+ channels are implicated in the release of CGRP from capsaicin-sensitive perivascular sensory nerves in response to acute hypotension, and that the released CGRP may contribute to the autoregulatory vasodilation in the cerebral microcirculation.

Retracing the evolution of amino acid specificity in glutaminyl-tRNA synthetase.

Molecular phylogenetic studies of glutaminyl-tRNA synthetase suggest that it has relatively recently evolved from the closely related enzyme glutamyl-tRNA synthetase. We have now attempted to retrace one of the key steps in this process by selecting glutaminyl-tRNA synthetase mutants displaying enhanced glutamic acid recognition. Mutagenesis of two residues proximal to the active site, Phe-90 and Tyr-240, was found to improve glutamic acid recognition 3-5-fold in vitro and resulted in the misacylation of tRNA(Gln) with glutamic acid. In vivo expression of the genes encoding these misacylating variants of glutaminyl-tRNA synthetase reduced cellular growth rates by 40%, probably as a result of an increase in translational error rates. These results provide the first biochemical evidence that glutaminyl-tRNA synthetase originated through duplication and consequent diversification of an ancestral glutamyl-tRNA synthetase-encoding gene.

Cysteinyl-tRNA formation: the last puzzle of aminoacyl-tRNA synthesis.

With the exception of the methanogenic archaea Methanococcus jannaschii and Methanobacterium thermoautotrophicum deltaH, all organisms surveyed contain orthologs of Escherichia coli cysteinyl-tRNA synthetase (CysRS). The characterization of CysRS-encoding (cysS) genes and the demonstration of their ability to complement an E. coli cysSts mutant reveal that Methanococcus maripaludis and Methanosarcina barkeri, two other methanogenic archaea, possess canonical CysRS proteins. A molecular phylogeny inferred from 40 CysRS sequences indicates that the CysRS of M. maripaludis and Methanosarcina spp. are specific relatives of the CysRS of Pyrococcus spp. and Chlamydia, respectively. This result suggests that the CysRS gene was acquired by lateral gene transfer in at least one euryarchaeotic lineage.

Translocational inefficiency of intracellular proteins in senescence of human diploid fibroblasts.

In order to investigate signal transduction pathways and related changes of actin cytoskeleton organization in cellular senescence, H-ras double mutants--V12S35, V12G37, and V12C40--were constitutively expressed in human foreskin fibroblast (HDF). Senescent HDF cells as well as the H-ras mutant expressers accumulated p-Erk1/2 in the cytoplasm with increased MEK activity and failed to translocate it to nuclei on EGF stimulation. Senescent HDF cells, V12S35 and V12G37 expressers, revealed a failure to export actin fiber from nucleus to cytoplasm and also to form stress fibers. Perinuclear expression of Rac1 was prominent in the HDF cells and V12C40 expresser; however, in the V12S35 expresser, translocation of Rac1 from perinucleus to nucleus and strong expression of RhoA were obvious. In summary, the H-ras double mutant expressers induced premature senescence through the MEK pathway, accompanied by nuclear accumulation of actin and Rac1 proteins, cytoplasmic retention of p-Erk1/2, and marked induction of RhoA expression, suggesting the translocational inefficiency of the intracellular proteins in the senescent HDF cells.

Enhancement of central and peripheral alpha 1-adrenoceptor sensitivity and reduction of alpha 2-adrenoceptor sensitivity following chronic imipramine treatment in rats.

After chronic imipramine treatment (20 mg/kg i.p., once daily for 14 days) the dose-response curve of the isolated rat anococcygeal muscle to phenylephrine shifted to the left, and furthermore, the -log KA value (affinity) for phenylephrine was significantly increased without affecting the affinity for guanfacine. On the other hand, such treatment caused a shift to the right of the dose-response curve to guanfacine on aortic strips and the affinity of the alpha-adrenoceptor for guanfacine was lowered without any accompanying changes in the affinity value for phenylephrine. However the relative efficacies of phenylephrine or guanfacine were not influenced by imipramine in either preparation. The ability of phenylephrine to displace [3H]prazosin from its specific binding sites was significantly enhanced after chronic imipramine treatment. These results may indicate that following chronic imipramine treatment the alpha 1-adrenoceptors of both central and peripheral tissues responded with supersensitivity to an alpha 1-preferential agonist, and the alpha 2-adrenoceptors with reduced sensitivity to an alpha 2-preferential agonist.

Effect of ouabain on relaxation induced by cromakalim in human and canine mesenteric arteries.

We investigated the effect of cromakalim, a K+ channel opener, that activates indirectly the Na(+)-K+ pump, in association with increased K+ conductance in the mesenteric arteries. In 65% of human mesenteric arteries tested, the concentration-dependent relaxation curves for cromakalim were biphasic: the low concentration (< 10(-7) M) effect was preferentially inhibited by ouabain, whereas the higher concentration effect was significantly inhibited by glibenclamide. In branches of canine mesenteric artery, the cromakalim-induced relaxation was inhibited by pretreatment with ouabain (1 microM) as well as by glibenclamide (1 microM). The reduction in contraction of human and canine mesenteric arterial strips caused by cromakalim was totally reversed by pretreatment with ouabain (1 microM) or glibenclamide (1 microM). On the other hand, in canine mesenteric artery, cromakalim caused a significant stimulation of 22Na+ influx and ouabain-sensitive 86Rb+ uptake in association with increased 86Rb+ efflux, all of which were inhibited by glibenclamide (1 microM). Thus, it is suggested that cromakalim possesses the additional property to stimulate the Na(+)-K+ pump through an elevation in intracellular Na+, resulting in strong relaxation of blood vessels.

SKP-450 inhibits migration and DNA synthesis stimulated by oxidized low density lipoprotein in smooth muscle cells.

This study was carried out to examine the inhibitory effects of SKP-450 (2-[2"(1", 3"-dioxolone)-2-methyl]-4-(2'-oxo-1'-pyrrolidinyl)-6-nitro-2H-1-be nzo pyran), a potassium channel opener, on the proliferation and migration stimulated by oxidized low density lipoprotein (LDL) of cultured smooth muscle cells of Wistar Kyoto rat aorta. SKP-450 (10(-7) and 10(-6) M) as well as probucol (10(-7)-10(-5) M) reduced the production of thiobarbituric acid reactive substances from LDL submitted to CuSO(4) (10 microM). The increased [3H]thymidine incorporation and migration (chemotactic and wound-edge) of the cultured smooth muscle cells in association with increased production of platelet-derived growth factor (PDGF)-BB-like immunoreactivity stimulated by oxidized LDL were significantly reduced by SKP-450 (10(-7)-10(-6) M). Inhibition by SKP-450 of the oxidized LDL-stimulated [3H]thymidine incorporation was antagonized by iberiotoxin (10(-7) M), but not by glibenclamide (10(-6) M), suggestive of mediation of Ca(2+)-activated K(+) channel opening in the action of SKP-450. Taken together, SKP-450 inhibited the proliferation and migration of the smooth muscle cells as well as PDGF production stimulated by oxidized LDL, accompanying with its antiperoxidative action.

Implication of adenosine A2A receptors in hypotension-induced vasodilation and cerebral blood flow autoregulation in rat pial arteries.

This study aimed to evaluate the role for adenosine A2A receptors in the autoregulatory vasodilation to hypotension in relation with cerebral blood flow (CBF) autoregulation in rat pial arteries. Changes in pial artery diameters were observed directly through a closed cranial window. Vasodilation induced by adenosine was markedly suppressed by ZM 241385 (1 micromol/l, A2A antagonist) and alloxazine (1 micromol/l, A2B antagonist), but not by 8-cyclopentyltheophylline (CPT, 1 micromol/l, A1 antagonist). CGS-21680-induced vasodilation was more strongly inhibited by ZM 241385 (25.3-fold; P<0.05) than by alloxazine. In contrast, 5'-N-ethylcarboxamido-adenosine (NECA)-induced vasodilation was more prominently suppressed by alloxazine (12.0-fold; P<0.001) than by ZM 241385. The autoregulatory vasodilation in response to acute hypotension of the pial arteries was significantly suppressed by ZM 241385, but not by CPT and alloxazine. Consistent with this finding, the lower limit of CBF autoregulation significantly shifted to a higher blood pressure by 1 micromol/l of ZM 241385 (53.0+/-3.9 mm Hg to 69.2+/-2.9 mm Hg, P<0.01) and 10 micromol/l of glibenclamide (54.7+/-6.5 mm Hg to 77.9+/-4.2 mm Hg, P<0.001), but not by CPT and alloxazine. Thus, it is suggested that adenosine-induced vasodilation of the rat pial artery is mediated via activation of adenosine A2A and A2B receptors, but not by A1 subtype, and activation of adenosine A2A receptor preferentially contributes to the autoregulatory vasodilation via activation of ATP-sensitive K+ channels in response to hypotension and maintenance of CBF autoregulation.

Involvement of NADH/NADPH oxidase-derived superoxide in experimental vasospasm induced by periarterial blood in rat femoral artery.

To elucidate the mechanism(s) involved in periarterial blood-mediated vasospasm in the rat femoral artery, vascular production of superoxide and related expression of intercellular adhesion molecule-1 (ICAM-1) were assessed with subsequent perivascular mobilization of granulocytes and macrophages. Arterial vasospasm characterized by increased wall thickness and decreased lumen size was observed on the side exposed to blood at 7 to 12 days, and these vascular changes were significantly ameliorated by pretreatment with NADH/NADPH oxidase inhibitor, diphenyleneiodonium (200 microM, locally). Increased mobilization of granulocytes was paralleled with the expression of ICAM-1 in the vessels at 24 hours after periarterial application of blood to the femoral artery, and then both declined. Subsequently, infiltration of macrophage progressively increased at all layers throughout 7 to 12 days. In in vitro study, a large amount of superoxide that was inhibitable by diphenyleneiodonium (20 and 100 microM) was produced at 3 hours upon application of 10% autologous blood to the aortic segments. Furthermore, ICAM-1 expression by autologous blood was well correlated with generation of superoxide anion in the aortic segment (r=0.975, P<0.05). Taken together, it is suggested that NADH/NADPH oxidase-derived superoxide is implicated in periarterial blood-induced vasospasm via increased expression of ICAM-1 with subsequent mobilization of granulocyte/macrophage.

Disturbances in autoregulatory responses of rat pial arteries by sulfonylureas.

It was aimed to test the role of ATP-sensitive K+ channels in the autoregulatory response of cerebral arterioles in vivo. Changes in pial arterial caliber (mean, 43.2 +/- 2.3 microns in diameter) in response to changes in systemic arterial blood pressure (mean, 104.3 +/- 1.4 mmHg) were observed directly through closed cranial windows in anesthetized normotensive rats. During superfusion with vehicle, pial arterial caliber automatically increased in response to hypotension induced by arterial bleeding into a reservoir and decreased on reverse of arterial blood pressure by infusion of blood. After pretreatment with sulfonylureas, glibenclamide (1 and 3 microM) and glipizide (30 and 100 microM), arteriolar dilatation and constriction observed during hypotension and its reverse were disturbed. A similarity was evidenced when hypotension was induced by sodium nitroprusside (750 nmol kg-1min-1, i.v.). Cromakalim, a K+ channel opener, exerted a concentration-dependent vasodilatation of the pial artery and its effect was antagonized by glibenclamide. These data suggest that the endogenous glibenclamide-sensitive K+ channel opener is involved in the modulation of cerebral microvascular autoregulation.

Decreased CGRP level with increased sensitivity to CGRP in the pial arteries of spontaneously hypertensive rats.

It was aimed to investigate the importance of calcitonin gene-related peptide (CGRP) in maintenance of normal cerebral microcirculation. We examined both the functional (in vivo) and biochemical effects (in vitro) of CGRP on the pial arteries of spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto rats (WKY). When mock cerebrospinal fluid containing capsaicin (3 x 10(-7) M) was suffused over the cortical surface, the diameter of pial arteries of SHR was transiently increased and rapidly returned to the baseline level, while the capsaicin-induced increase in pial arterial diameters of WKY was large and sustained for a longer duration (> 10 min). Capsaicin-induced vasodilation was significantly attenuated by pretreatment with CGRP8-37, a CGRP1, receptor antagonist, in both WKY and SHR. On the other hand, cortical suffusion with CGRP (10(-9) approximately 10(-6) M) exerted a larger enhancement in the vasodilation of pial artery of SHR than WKY. The CGRP-induced vasodilation was significantly antagonized by CGRP8-37 in both WKY and SHR. The released level of CGRP-like immunoreactivity (CGRP-LI) from the pial artery was significantly lower in SHR (12.3 +/- 1.2 fmol/mm2/hr) than that in WKY (24.5 +/- 3.9 fmol/mm2/hr). CGRP (10(-6) M)-induced stimulation of cyclic AMP formation was rather larger in the pial arteries from SHR (50.2 +/- 5.8 fmol/mm2/30 min, p < 0.05) than those from WKY (34.5 +/- 3.8 fmol/mm2/30 min). These data suggest that, in the pial arteries of SHR, the transient vasodilation to capsaicin and enhanced vasodilation to CGRP are related to the decreased CGRP level in the cerebral microvascular beds, consequently leading to increased sensitivity of the CGRP receptors to CGRP.