Synergistic therapeutic vascular cytoprotection against complement-mediated injury induced via a PKCα-, AMPK-, and CREB-dependent pathway.

Endothelial injury and dysfunction precede accelerated arterial disease in allograft vasculopathy and systemic autoimmune diseases and involve pathogenic Abs and complement. Recent reports suggest that switching to rapamycin from calcineurin antagonists reduces posttransplant vasculopathy and prolongs survival following cardiac transplantion. The majority of these patients also receive statin therapy. We examined potential mechanisms underlying this protective response in human endothelial cells and identified synergy between rapamycin and atorvastatin. Mechanistically, atorvastatin and rapamycin activated a protein kinase Cα, AMP-activated kinase, and CREB-dependent vasculoprotective pathway, which induced decay-accelerating factor (DAF) promoter activity via binding to the cAMP response element, mutation of which attenuated promoter activity. This response significantly increased endothelial cell surface DAF and enhanced protection against complement-mediated injury. Synergy with rapamycin was reproduced by simvastatin, whereas combining atorvastatin with cyclosporine or mycophenolate in place of rapamycin was ineffective. Importantly, synergy was reproduced in vivo, in which only atorvastatin and rapamycin therapy in combination was sufficient to induce DAF on murine aortic endothelium. We believe this pathway represents an important therapeutically inducible vasculoprotective mechanism for diseases mediated by pathogenic Abs and complement, including posttransplant vasculopathy and systemic lupus erythematosus. Although our study focuses on the vascular endothelium, the findings are likely to be broadly applicable, given the diverse cellular expression of DAF.

Protein kinase Cε activity induces anti-inflammatory and anti-apoptotic genes via an ERK1/2- and NF-κB-dependent pathway to enhance vascular protection.

Vascular endothelial injury predisposes to endothelial dysfunction and atherogenesis. We have investigated the hypothesis that PKCε (protein kinase Cε) is an important upstream regulator of cytoprotective pathways in vascular ECs (endothelial cells). Depletion of PKCε in human ECs reduced expression of the cytoprotective genes A1, A20 and Bcl-2. Conversely, constitutively active PKCε expressed in human ECs increased mRNA and protein levels of these cytoprotective genes, with up-regulation dependent upon ERK1/2 (extracellular-signal-regulated kinase 1/2) activation. Furthermore, inhibition of NF-κB (nuclear factor κB) by the pharmacological antagonist BAY 11-7085 or an IκB (inhibitor of NF-κB) SuperRepressor prevented cytoprotective gene induction. Activation of PKCε enhanced p65 NF-κB DNA binding and elevated NF-κB transcriptional activity. Importantly, although NF-κB activation by PKCε induced cytoprotective genes, it did not up-regulate pro-inflammatory NF-κB targets [E-selectin, VCAM-1 (vascular cell adhesion molecule 1) and ICAM-1 (intercellular adhesion molecule 1)]. Indeed, PKCε exhibited cytoprotective and anti-inflammatory actions, including inhibition of TNFα (tumour necrosis factor α)-induced JNK (c-Jun N-terminal kinase) phosphorylation and ICAM-1 up-regulation, a response attenuated by depletion of A20. Thus we conclude that PKCε plays an essential role in endothelial homoeostasis, acting as an upstream co-ordinator of gene expression through activation of ERK1/2, inhibition of JNK and diversion of the NF-κB pathway to cytoprotective gene induction, and propose that PKCε represents a novel therapeutic target for endothelial dysfunction.

Reactive oxygen species are necessary for high flow (shear stress)-induced diameter enlargement of rat resistance arteries.

OBJECTIVES: Chronic increases in blood flow induce remodeling associated with increases in diameter and endothelium-mediated dilation. Remodeling requires cell growth and migration, which may involve reactive oxygen species (ROS). Nevertheless, the role of ROS in flow-mediated remodeling in resistance arteries is not known. MATERIALS AND METHODS: Rat mesenteric resistance arteries (MRAs) were exposed to high flow (HF) by sequentially ligating second-order MRAs in vivo. After three weeks, arteries were collected for structural, pharmacological, and biochemical analysis. RESULTS: In HF arteries, luminal diameter (431+/-12 to 553+/-14 microm; n=10), endothelium (acetylcholine)-mediated vasodilatation (61+/-6 to 77+/-6% relaxation) and NAD(P)H subunit (gp91phox and p67phox) expression levels, and ROS (dihydroethydine microphotography) and peroxynitrite (3-nitro-tyrosine) production were higher than in normal flow arteries. Acute ROS scavenging with tempol improved acetylcholine-dependent relaxation (92+/-4% relaxation), confirming that ROS are produced in HF arteries. Chronic treatment with tempol prevented the increase in diameter, reduced ROS and peroxynitrite production, and improved endothelium-mediated relaxation in HF arteries. Thus, ROS and NO were involved in HF-induced diameter enlargement, possibly through the formation of peroxynitrite, while ROS reduced the increase in endothelium-dependent relaxation. CONCLUSIONS: ROS production is necessary for flow-mediated diameter enlargement of resistance arteries. However, ROS counteract, in part, the associated improvement in endothelium-mediated relaxation.

Alteration in flow (shear stress)-induced remodelling in rat resistance arteries with aging: improvement by a treatment with hydralazine.

AIMS: The link between aging and vascular diseases remains unclear, especially in resistance arteries. As a decreased vasodilator capacity of the endothelium is usually described in aging, we hypothesized that arteriolar remodelling in response to a chronic increase in blood flow might be altered. In addition, we tested the capacity of a vasodilator treatment with hydralazine to restore remodelling, as we have previously shown that hydralazine has a potent effect on the process. METHODS AND RESULTS: Mesenteric resistance arteries (350 microm diameter) from 3- and 24-month-old rats were exposed to high blood flow (HF) and normal blood flow (NF), for 2 weeks by sequential ligating second-order arteries in vivo. In HF arteries, diameter increased by 21% when intraluminal pressure was 100 mmHg, in association with a rise in superoxide production in young rats. On the other hand, both diameter and superoxide levels failed to increase in old rats. Hydralazine restored HF-induced remodelling in old rats in association with an increased superoxide production and a decreased superoxide dismutase (SOD) expression. The SOD-mimetic 4-hydroxy-2,2,6,6-tetramethyl piperidinoxyl (TEMPOL) prevented the effect of hydralazine on the arterial diameter. In old rats, hydralazine increased the arterial diameter in HF arteries without increasing eNOS expression. Furthermore, hydralazine also restored HF remodelling in eNOS knockout mice. CONCLUSION: Thus, flow remodelling in resistance arteries failed to occur in aging but it could be restored by hydralazine via a reactive oxygen species-dependent mechanism. These findings may have serious pathophysiological consequences in situations requiring flow-dependent remodelling such as ischaemic and metabolic diseases, more frequent in the elderly.

Key role of the NO-pathway and matrix metalloprotease-9 in high blood flow-induced remodeling of rat resistance arteries.

OBJECTIVE: Blood flow is altered in metabolic and ischemic diseases with dramatic consequences. Resistance arteries structure and function remodel in response to chronic blood flow changes through a mechanism remaining mainly unknown. We hypothesized that the NO pathway and matrix metalloproteases (MMPs) activation might play a role in flow (shear stress)-induced microvascular remodeling. METHODS AND RESULTS: Mesenteric resistance arteries were ligated to alter blood flow in vivo for 4 or 14 days: arteries were submitted to high (HF), low (LF), or normal flow (NF). Rats were treated with L-NAME, the angiotensin converting enzyme inhibitor perindopril or the MMPs inhibitor doxycycline. After 14 days, outward hypertrophic remodeling occurred in HF arteries in association with eNOS overexpression. MMP9 activity increased in the early phase (day 4). HF-remodeling was prevented by L-NAME, eNOS gene knockout, and doxycycline. L-NAME prevented eNOS overexpression and MMPs activation whereas doxycycline only prevented MMPs activation. In LF arteries diameter reduction was associated with a decreased eNOS expression without change in MMPs expression and activation. LF-remodeling was reduced by perindopril. CONCLUSIONS: In resistance arteries, high flow induced diameter enlargement and wall hypertrophy associated with the sequential activation of eNOS and MMP9.

[Assessment of antibiotic prescriptions in the emergency department of a general hospital. Prospective analysis of 211 prescriptions]. / Evaluation de la qualité des prescriptions antibiotiques dans le service d'accueil des urgences d'un centre hospitalier général. Analyse prospective de 211 prescriptions.

AIM: To study the appropriateness and conformity to antibiotic prescription guidelines in an emergency department and to assess the factors likely to influence them. METHODS: This prospective study included all adult patients visiting the emergency department over a period of 100 days and receiving antibiotic treatment. Two independent specialists in infectious disease assessed the appropriateness of the indications and the treatment's conformity with good practice guidelines. We also studied patient's status 7 days after initiation of antibiotic treatment, duration of hospitalization and any treatment changes. RESULTS: The study included 211 patients, 47% of them men. Prescriptions were appropriate in 53% of cases and in accordance with guidelines in 34%. Half of all prescriptions were related to urinary tract or pulmonary infections. Four antibiotic families accounted for 88% of prescriptions. Prescription errors were related to multidrug treatments, intravenous drugs, and inappropriate antibiotic families. More than half (56%) of the patients were admitted, and 70% of these remained in the hospital more than one week. Duration of treatment was inappropriate for 31% of the patients not admitted. In all, 44% of the antibiotic prescriptions ordered in the emergency department were later modified. CONCLUSION: Multidisciplinary work is essential in improving the quality of antibiotic prescriptions in an emergency department.

Effectiveness of a Multimodal Intervention Program for Older Individuals Presenting to the Emergency Department After a Fall in the Northern French Alps Emergency Network.

OBJECTIVE: Fall-related visits to emergency departments (EDs) are common among older individuals. We aimed to assess effectiveness of a healthcare intervention program for the management of elderly patients admitted to EDs after a fall. METHODS: Using a before-after observation method, we investigated ED healthcare staff practices related to fall-related injuries in 2010 (period 1) and 2012 (period 2) in 13 centers participating in the Northern French Alps Emergency Network. Following the identification of initial weaknesses, several information and training tools were introduced between the two periods to improve patient management. All individuals aged 75 years or over who presented to an ED after a fall were included in the study. We reviewed the completeness and quality of medical records during both periods and compared the rate of clinical-paraclinical check-ups performed, geriatric evaluation/assessment in the ED, and the 1-month recurrence of visits to the ED for the same reason. RESULTS: During period 1, a total of 2,425 falls were recorded, while 2,684 were reported in period 2. The 2012 medical charts contained significantly more information about risk factors than those of 2010. An electrocardiogram (64% vs. 53%; p < 0.001), biologic check-up (65% vs. 57%; p < 0.001), balance, orthostatic hypotension, and cognitive impairment tests were more often performed in 2012. There was no change in the hospitalization rate, although short-duration hospitalization in the ED was more frequent in 2012. Geriatrists were more often consulted by patients in 2012 (18% vs. 13%; p < 0.001) and more involved in ED evaluation and hospitalization. The intervention program had a beneficial impact on the fall recurrence rate (n = 29 [3.6%] in period 1 and n = 17 [2.0%] in period 2; odds ratio = 0.52; p = 0.037), which significantly decreased between 2010 and 2012. CONCLUSIONS: The intervention program was associated with a decrease of fall recurrence. Further efforts should be made in EDs to ensure a sustained level of satisfactory and long-lasting management of the elderly.

PKCε-CREB-Nrf2 signalling induces HO-1 in the vascular endothelium and enhances resistance to inflammation and apoptosis.

AIMS: Vascular injury leading to endothelial dysfunction is a characteristic feature of chronic renal disease, diabetes mellitus, and systemic inflammatory conditions, and predisposes to apoptosis and atherogenesis. Thus, endothelial dysfunction represents a potential therapeutic target for atherosclerosis prevention. The observation that activity of either protein kinase C epsilon (PKCε) or haem oxygenase-1 (HO-1) enhances endothelial cell (EC) resistance to inflammation and apoptosis led us to test the hypothesis that HO-1 is a downstream target of PKCε. METHODS AND RESULTS: Expression of constitutively active PKCε in human EC significantly increased HO-1 mRNA and protein, whereas conversely aortas or cardiac EC from PKCε-deficient mice exhibited reduced HO-1 when compared with wild-type littermates. Angiotensin II activated PKCε and induced HO-1 via a PKCε-dependent pathway. PKCε activation significantly attenuated TNFα-induced intercellular adhesion molecule-1, and increased resistance to serum starvation-induced apoptosis. These responses were reversed by the HO antagonist zinc protoporphyrin IX. Phosphokinase antibody array analysis identified CREB1((Ser133)) phosphorylation as a PKCε signalling intermediary, and cAMP response element-binding protein 1 (CREB1) siRNA abrogated PKCε-induced HO-1 up-regulation. Likewise, nuclear factor (erythroid-derived 2)-like 2 (Nrf2) was identified as a PKCε target using nuclear translocation and DNA-binding assays, and Nrf2 siRNA prevented PKCε-mediated HO-1 induction. Moreover, depletion of CREB1 inhibited PKCε-induced Nrf2 DNA binding, suggestive of transcriptional co-operation between CREB1 and Nrf2. CONCLUSIONS: PKCε activity in the vascular endothelium regulates HO-1 via a pathway requiring CREB1 and Nrf2. Given the potent protective actions of HO-1, we propose that this mechanism is an important contributor to the emerging role of PKCε in the maintenance of endothelial homeostasis and resistance to injury.

Time-related alteration in flow- (shear stress-) mediated remodeling in resistance arteries from spontaneously hypertensive rats.

Hypertension is a major risk factor for cardiovascular disorders. As flow-mediated outward remodeling has a key role in postischemic revascularization, we investigated this remodeling in mesenteric resistance arteries of normotensive (WKY) and spontaneously hypertensive rats (SHRs) aged 3 to 9 months. Sequential ligation of mesenteric resistance arteries allowed modifying blood flow in vivo, thus exposing arteries to low, normal, or high flow. After 1, 3, 8, or 24 weeks, arteries were isolated for in vitro study. High flow (HF) induced outward hypertrophic remodeling in WKY rats after 1 week and persisted until 24 weeks without change in wall to lumen ratio. In SHRs, diameter increase was delayed, occurring only after 3 weeks. Nevertheless, it was reduced at 8 weeks and no longer significant after 24 weeks. In parallel, media cross-section area increased more with time in SHRs than in WKY rats and this was associated with increased contractility and oxidative stress with decreased NO-dependent relaxation. Low flow induced progressive inward remodeling until 24 weeks in both strains with excessive hypertrophy in SHRs. Thus, a chronic increase in flow induced transitory diameter expansion and long-lasting hypertrophy in SHRs. This could contribute to the higher susceptibility of hypertensive subjects to ischemic diseases.

Role of angiotensin II in the remodeling induced by a chronic increase in flow in rat mesenteric resistance arteries.

Angiotensin II is a potent growth factor involved in arterial wall homeostasis. In resistance arteries, chronic increases in blood flow induce a rise in diameter associated with arterial wall hypertrophy. Nevertheless, the role of angiotensin II in this remodeling is unknown. We investigated the effect of blocking angiotensin II production or receptor activation on flow-induced remodeling of mesenteric resistance arteries. Arteries were ligated in vivo to generate high-flow arteries compared with normal flow (control) vessels located at a distance. Arteries were isolated after 1 week for in vitro analysis. Arterial diameter, media surface, endothelial NO synthase expression, superoxide production, and extracellular signal-regulated kinase 1/2 phosphorylation were higher in high-flow than in control arteries. Angiotensin-converting enzyme inhibition (perindopril) and angiotensin II type 1 receptor blockade (candesartan) prevented arterial wall hypertrophy without affecting diameter enlargement. The nonselective vasodilator hydralazine had no effect on remodeling. Although perindopril and candesartan increased endothelial NO synthase expression in high-flow arteries, hypertrophy remained in rats treated with N(G)-nitro-l-arginine methyl ester and mice lacking endothelial NO synthase. Perindopril and candesartan reduced oxidative stress in high-flow arteries, but superoxide scavenging did not prevent hypertrophy. Both Tempol and the absence of endothelial NO synthase prevented the rise in diameter in high-flow vessels. Extracellular signal-regulated kinase 1/2 activation in high-flow arteries was prevented by perindopril and candesartan and not by hydralazine. Extracellular signal-regulated kinase 1/2 inhibition in vivo (U0126) prevented hypertrophy in high-flow arteries. Thus, a chronic rise in blood flow in resistance arteries induces a diameter enlargement involving NO and superoxide, whereas hypertrophy was associated with extracellular signal-regulated kinase 1/2 activation by angiotensin II.

Involvement of angiotensin II in the remodeling induced by a chronic decrease in blood flow in rat mesenteric resistance arteries.

Blood flow reduction induces inward remodeling of resistance arteries (RAs). This remodeling occurs in ischemic diseases, diabetes and hypertension. Nonetheless, the effect of flow reduction per se, independent of the effect of pressure or metabolic influences, is not well understood in RA. As angiotensin II is involved in the response to flow in RA, we hypothesized that angiotensin II may also be involved in the remodeling induced by a chronic flow reduction. We analyzed the effect of angiotensin I-converting enzyme inhibition (perindopril) and angiotensin II type 1 receptor blockade (candesartan) on inward remodeling induced by blood flow reduction in vivo in rat mesenteric RAs (low flow (LF) arteries). After 1 week, diameter reduction in LF arteries was associated with reduced endothelium-dependent relaxation and lower levels of eNOS expression. Superoxide production and extracellular signal-regulated kinases 1/2 (ERK1/2 phosphorylation were higher in LF than in normal flow arteries. Nevertheless, the absence of eNOS or superoxide level reduction (tempol or apocynin) did not prevent LF remodeling. Perindopril and candesartan prevented inward remodeling in LF arteries. Contractility to angiotensin II was reduced in LF vessels by perindopril, candesartan and the ERK1/2 blocker PD98059. ERK1/2 activation (ratio phospho-ERK/ERK) was higher in LF arteries, and this activation was prevented by perindopril and candesartan. ERK1/2 inhibition in vivo (U0126) prevented LF-induced diameter reduction. Thus, inward remodeling because of blood flow reduction in mesenteric RA depends on unopposed angiotensin II-induced contraction and ERK1/2 activation, independent of superoxide production. These findings might be of importance in the treatment of vascular disorders.

Celecoxib activates PI-3K/Akt and mitochondrial redox signaling to enhance heme oxygenase-1-mediated anti-inflammatory activity in vascular endothelium.

Although nonsteroidal anti-inflammatory drugs (NSAIDs) provide important control of pain and inflammation, they have been overshadowed by concerns regarding atherothrombotic complications. However, celecoxib seems to have a relatively good cardiovascular profile and may improve endothelial function in coronary heart disease. This led us to the hypothesis that celecoxib induces the vasculoprotective enzyme heme oxygenase-1 (HO-1). In human umbilical vein and aortic endothelial cells, 24-48 h treatment with celecoxib induced HO-1 mRNA and protein expression and increased HO-1 enzyme activity. This effect was not seen with rofecoxib or indomethacin. Supplementation of culture medium with iloprost or prostaglandin E(2) failed to reverse celecoxib-mediated HO-1 induction, indicating a cyclooxygenase-independent mechanism. Rather, this action of celecoxib involved generation of mitochondria-derived reactive oxygen species, Akt phosphorylation, and nuclear translocation of the transcription factor Nrf2, with N-acetylcysteine, PI-3K antagonist LY290042, and dominant-negative Akt abrogating the effects. Furthermore, celecoxib-induced HO-1 was inhibited by dominant-negative Nrf2. The functional significance of HO-1 induction was revealed by celecoxib-mediated inhibition of VCAM-1 expression, a response reversed by the HO-1 antagonist zinc protoporphyrin. HO-1 induction provides a molecular mechanism for clinical observations indicating relative freedom from atherothrombotic complications in patients taking celecoxib compared to other NSAIDs with comparable anti-inflammatory activity.

Key role of alpha(1)beta(1)-integrin in the activation of PI3-kinase-Akt by flow (shear stress) in resistance arteries.

Resistance arteries are the site of the earliest manifestations of many cardiovascular and metabolic diseases. Flow (shear stress) is the main physiological stimulus for the endothelium through the activation of vasodilatory pathways generating flow-mediated dilation (FMD). The role of FMD in local blood flow control and angiogenesis is well established, and alterations in FMD are early markers of cardiovascular disorders. alpha(1)-Integrin, which has a role in angiogenesis, could be involved in FMD. FMD was studied in mesenteric resistance arteries (MRA) isolated in arteriographs. The role of alpha(1)-integrins in FMD was tested with selective antibodies and mice lacking the gene encoding for alpha(1)-integrins. Both anti-alpha(1) blocking antibodies and genetic deficiency in alpha(1)-integrin in mice (alpha(1)(-/-)) inhibited FMD without affecting receptor-mediated (acetylcholine) endothelium-dependent dilation or endothelium-independent dilation (sodium nitroprusside). Similarly, vasoconstrictor tone (myogenic tone and phenylephrine-induced contraction) was not affected. In MRA phosphorylated Akt and phosphatidylinositol 3-kinase (PI3-kinase) were significantly lower in alpha(1)(-/-) mice than in alpha(1)(+/+) mice, although total Akt and endothelial nitric oxide synthase (eNOS) were not affected. Pharmacological blockade of PI3-kinase-Akt pathway with LY-294002 inhibited FMD. This inhibitory effect of LY-294002 was significantly lower in alpha(1)(-/-) mice than in alpha(1)(+/+) mice. Thus alpha(1)-integrin has a key role in flow (shear stress)-dependent vasodilation in resistance arteries by transmitting the signal to eNOS through activation of PI3-kinase and Akt. Because of the central role of flow (shear stress) activation of the endothelium in vascular disorders, this finding opens new perspectives in the pathophysiology of the microcirculation and provides new therapeutic targets.

Paradoxical role of angiotensin II type 2 receptors in resistance arteries of old rats.

The role of angiotensin II type 2 receptors (AT2Rs) remains a matter of controversy. Its vasodilatory and antitrophic properties are well accepted. Nevertheless, in hypertensive rats, AT2R stimulation induces a vasoconstriction counteracting flow-mediated dilation (FMD). This contraction is reversed by hydralazine. Because FMD is also decreased in aging, another risk factor for cardiovascular diseases, we hypothesized that AT2R function might be altered in old-rat resistance arteries. Mesenteric resistance arteries (250 mum in diameter) were isolated from old (24 months) and control (4 months) rats receiving hydralazine (16 mg/kg per day; 2 weeks) or water. FMD, NO-mediated dilation, and endothelial NO synthase expression were lower in old versus control rats. AT2R blockade improved FMD in old rats, suggesting that AT2R stimulation produced vasoconstriction. AT2R expression was higher in old rats and mainly located in the smooth muscle layer. In old rats, AT2R stimulation induced endothelium-independent contraction, which was suppressed by the antioxidant Tempol. Reactive oxygen species level was higher in old-rat arteries than in controls. Hydralazine improved FMD and NO-dependent dilation in old rats without change in AT2R expression and location. In old rats treated with hydralazine, reactive oxygen species level was reduced in endothelial and smooth muscle cells, and AT2R-dependent contraction was abolished. Thus, AT2R stimulation induced vasoconstriction through activation of reactive oxygen species production, contributing to decrease FMD in old-rat resistance arteries. Hydralazine suppressed AT2R-dependent reactive oxygen species production and AT2R-dependent contraction, improving FMD. Importantly, endothelial alterations in aging were reversible. These findings are important to consider in the choice of vasoactive drugs in aging.

Flow-induced remodeling in resistance arteries from obese Zucker rats is associated with endothelial dysfunction.

Chronic increases in blood flow increase arterial diameter and NO-dependent dilation in resistance arteries. Because endothelial dysfunction accompanies metabolic syndrome, we hypothesized that flow-mediated remodeling might be impaired in obese rat resistance arteries. Obese and lean Zucker rat mesenteric resistance arteries were exposed to chronic flow increases through arterial ligation in vivo: arteries exposed to high flow were compared with normal flow arteries. Diameter was measured in vitro in cannulated arteries using pressure arteriography. After 7 days, outward remodeling (diameter increased from 346+/-9 to 412+/-11 mum at 100 mm Hg) occurred in lean high-flow arteries. Endothelium-dependent tone was reduced in high-flow arteries from obese rats by contrast with lean animals. On the other hand, diameter enlargement occurred similarly in the 2 strains. The involvement of NO in endothelium-dependent dilation (evidenced by NO blockade) and endothelial NO synthase phosphorylation was smaller in obese than in lean rats. Superoxide anion and reduced nicotinamide-adenine dinucleotide phosphate oxidase subunit expression (p67phox and gp91phox) increased in obese rats and were higher in high-flow than in control arteries. Acute Tempol (a catalase mimetic), catalase plus superoxide dismutase, and l-arginine plus tetrahydrobiopterin restored endothelium-dependent dilation in obese rat normal and high-flow arteries to the level found in lean control arteries. Thus, flow-induced remodeling in obese resistance arteries was associated with a reduced endothelium-mediated dilation because of a decreased NO bioavailability and an excessive superoxide production. This dysfunction might have negative consequences in ischemic diseases in patients with obesity or metabolic syndrome.

Fatty acid alterations in liver peroxisomes from n-3-deficient mice.

A diet deficient in n-3 fatty acids dramatically reduces docosahexaenoic acid (4.8-fold) and 20:5n-3 content in murine total peroxisomal phospholipids, and conversely increases 22:5n-6 (17.1-fold) and also, to a lesser extent, 20:4n-6. This was also found in purified phosphatidylethanolamine and phosphatidylcholine. After changing the non-deficient diet (containing alpha-linolenic acid, ALA) to a deficient one (deficient in ALA), it took a very long time for docosahexaenoic acid concentration in peroxisomes to decline (>5 months). In contrast, after changing the deficient to a non-deficient diet, time to complete recovery was more rapid (3 weeks). Changes in 20:5n-3, 22:6n-3 and 20:4n-6 were generally stabilized within 2-4 weeks. Dietary n-3 fatty acids control the fatty acid composition of peroxisomal membranes, and thus possibly affect some of their functions.

Cellular mechanisms underlying cutaneous pressure-induced vasodilation: in vivo involvement of potassium channels.

In the skin of humans and rodents, local pressure induces localized cutaneous vasodilation, which may be protective against pressure-induced microvascular dysfunction and lesion formation. Once activated by the local pressure application, capsaicin-sensitive nerve fibers release neuropeptides that act on the endothelium to synthesize and release nitric oxide (NO) and prostaglandins, leading to the development of the cutaneous pressure-induced vasodilation (PIV). The present study was undertaken to test in vivo the hypothesis that PIV is mediated or modulated by differential activation of K+ channels in anesthetized rats using pharmacological methods. Local pressure was applied at 11.1 Pa/s. Endothelium-independent and -dependent vasodilation were tested using iontophoretic delivery of sodium nitroprusside (SNP) and acetylcholine (ACh), respectively, and was correlated with PIV response. PIV was reduced after systemic administration of tetraethylammonium (a nonspecific K+ channel blocker), iberiotoxin [a specific large-conductance Ca2+-activated K+ (BKCa) channel blocker], and glibenclamide [a specific ATP-sensitive K+ (KATP) channel blocker], whereas PIV was unchanged by apamin (a specific small-conductance Ca2+-activated K+ channel blocker) and 4-aminopyridine (a specific voltage-sensitive K+ channel blocker). The responses to SNP and ACh were reduced by iberiotoxin but were unchanged by glibenclamide. We conclude that the cellular mechanism of PIV in skin involves BKCa and KATP channels. We suggest that the opening of BKCa and KATP channels contributes to the hyperpolarization of vascular smooth muscle cells to produce PIV development mainly via the NO and prostaglandin pathways, respectively.

Dose-effect of dietary oleic acid: oleic acid is conditionally essential for some organs.

The minimum dietary intake of oleic acid that is indispensable to maintain a normal content of this fatty acid in several tissues (heart, muscle, kidney and testis) was determined in the rat. For this purpose, a dose-effect study was conducted using an experimental protocol with 7 groups of rats who received a diet in which the oleic acid level varied from 0 to 6000 mg per 100 g diet, but the other ingredients were identical (in particular the essential fatty acids, linoleic and alpha-linolenic acid). Female rats were fed the diets from two weeks before mating, and their pups were killed aged either 21 or 60 days. When the level of oleic acid in the diet was increased, the main modifications observed in 21-day-old deficient pups were as follows: (i) for 18:1n-9, in the liver, muscle, heart, kidney, and testis, a plateau was reached at about 4 g oleic acid per 100 g diet. Below this level, the higher the dose the greater the response; (ii) for 16:1n-7, the concentration decreased in the liver, muscle, heart, kidney and testis; (iii) the concentration of 18:1n-7 decreased in the kidney, muscle, and testis; (iv) some minor modifications were noted for the other fatty acids. In mother's milk at 14 days of lactation, when dietary oleic acid increased, the levels of 18:1(n-9) also increased; the increase was regular and did not reach a plateau. In 60-day-old rats, the results were generally similar to those in 21-day-old rats, but with some differences, in particular a slight decrease in oleic acid concentration in the liver and kidney at the highest dietary oleic acid level.