An exploratory study of structural and microvascular changes in the skin following electrical shaving using optical coherence topography.

BACKGROUND: Consumer products such as electrical shavers exert a combination of dynamic loading in the form of pressure and shear on the skin. This mechanical stimulus can lead to discomfort and skin tissue responses characterised as "Skin Sensitivity". To minimise discomfort following shaving, there is a need to establish specific stimulus-response relationships using advanced tools such as optical coherence tomography (OCT). OBJECTIVE: To explore the spatial and temporal changes in skin morphology and microvascular function following an electrical shaving stimulus. METHODS: Ten healthy male volunteers were recruited. The study included a 60-s electrical shaving stimulus on the forearm, cheek and neck. Skin parameters were recorded at baseline, 20 min post stimulus and 24 h post stimulus. Structural and dynamic skin parameters were estimated using OCT, while transepidermal water loss (TEWL) was recorded to provide reference values for skin barrier function. RESULTS: At baseline, six of the eight parameters revealed statistically significant differences between the forearm and the facial sites, while only surface roughness (Rq) and reflectivity were statistically different (p < 0.05) between the cheek and neck. At 20 min post shaving, there was a significant increase in the TEWL values accompanied by increased blood perfusion, with varying magnitude of change dependent on the anatomical site. Recovery characteristics were observed 24 h post stimulus with most parameters returning to basal values, highlighting the transient influence of the stimulus. CONCLUSIONS: OCT parameters revealed spatial and temporal differences in the skin tissue response to electrical shaving. This approach could inform shaver design and prevent skin sensitivity.

Influence of the Topographic Vascular Distribution of the Face on Dermal Filler Accidents.

OBJECTIVE: Dermal fillers are an important tool in the field of aesthetic dermatology. Fillers are relatively noninvasive and easy to use but are not free of secondary complications. The main complications are vascular and are due to either the compression of an artery or the direct introduction of the product into the arterial lumen. The aim of this study is to provide an overview of the vascular territories of the face to avoid many possible complications when using facial fillings. Anatomical localization of the main arterial supply to the face has been described to assess the risk of vascular injury. METHODS: The authors dissected 17 hemifaces of embalmed adult cadavers that had previously been injected, through the common carotid artery, with latex containing a red dye. RESULTS: A topographic distribution was generated by facial regions following a clinical approach from where the facial fillings were placed and related to the pathways of the arteries. Following these criteria, we established 8 topographic regions (I-VIII) that indicate the main vascular problems of each of these regions. Detailed anatomical localizations of the main arteries in these topographic regions of the face and their relationships are described. CONCLUSIONS: The highest index of vascular lesions and especially visual alterations occurred for fillings of the upper third of the face. To prevent and avoid this type of lesion, it is advisable to avoid, as much as possible, treatments with filling materials in the upper third of the face, mainly including the glabellar and nasal region (III) and supraorbital region (VIII).

Lesions of the Parotid Gland and Buccal Artery After Buccal Fat Pad Reduction.

The significant increase in esthetic surgery, especially buccal fat pad reduction, has led to a corresponding increase in lesions and postoperatory after-effects from this surgical procedure. The aim of this study is to discuss the immediate and mediate risks of removing the Bichat ball, as well as describing a clinical study in which this surgical procedure resulted in lesions of the parotid gland and buccal artery, which was confirmed via nuclear magnetic resonance. The facial lesions were remedied via exploratory surgery by opening a new orifice of the glandular duct in the buccal cavity followed by drainage and compressive surgical bandages.

Nitrosative stress uncovers potent ß2-adrenergic receptor-linked vasodilation further enhanced by blockade of clathrin endosome formation.

This study investigated the effect of sodium nitroprusside (SNP) preexposure on vasodilation via the ß-adrenergic receptor (BAR) system. SNP was used as a nitrosative/oxidative proinflammatory insult. Small arterioles were visualized by intravital microscopy in the hamster cheek pouch tissue (isoflurane, n = 45). Control dilation to isoproterenol (EC50: 10-7 mol/l) became biphasic as a function of concentration after 2 min of exposure to SNP (10-4 M), with increased potency at picomolar dilation uncovered and decreased efficacy at the micromolar dilation. Control dilation to curcumin was likewise altered after SNP, but only the increased potency at a low dose was uncovered, whereas micromolar dilation was eliminated. The picomolar dilations were blocked by the potent BAR-2 inverse agonist carazolol (10-9 mol/l). Dynamin inhibition with dynasore mimicked this effect, suggesting that SNP preexposure prevented BAR agonist internalization. Using HeLa cells transfected with BAR-2 tagged with monomeric red fluorescent protein, exposure to 10-8-10-6 mol/l curcumin resulted in internalization and colocalization of BAR-2 and curcumin (FRET) that was prevented by oxidative stress (10-3 mol/l CoCl2), supporting that stress prevented internalization of the BAR agonist with the micromolar agonist. This study presents novel data supporting that distinct pools of BARs are differentially available after inflammatory insult. NEW & NOTEWORTHY Preexposure to an oxidative/nitrosative proinflammatory insult provides a "protective preconditioning" against future oxidative damage. We examined immediate vasoactive and molecular consequences of a brief preexposure via ß-adrenergic receptor signaling in small arterioles. Blocked receptor internalization with elevated reactive oxygen levels coincides with a significant and unexpected vasodilation to ß-adrenergic agonists at picomolar doses.

Effects of Selenium in the Microcirculation of Fructose-Fed Hamsters.

BACKGROUND AND AIMS: Fructose intake is directly related to vascular dysfunction and it is a risk factor for the development of metabolic and cardiovascular diseases, such as obesity, diabetes, and hypertension. Selenium, a component of antioxidant enzymes, improves hyperglycemia and vascular function in diabetic animals. The aim of this study was to evaluate the effects of dietary selenium supplementation on microcirculatory and metabolic parameters of fructose-fed hamsters. METHODS AND RESULTS: Male hamsters (Mesocricetus auratus) had their drinking water substituted or not by 10% fructose solution for 60 days, during which their microcirculatory function was evaluated in the cheek pouch preparation. Blood glucose and serum insulin levels were also tested. Microcirculatory responses to acetylcholine (an endothelium-dependent vasodilator) and to sodium nitroprusside (SNP, an endothelium-independent vasodilator), and macromolecular permeability increase induced by a 30-min ischemia/reperfusion (I/R) procedure, showed that endothelium-dependent and independent vasodilatation was significantly increased in animals that had high selenium supplementation, in both the control and fructose-fed groups. Selenium supplementation protected against plasma leakage induced by I/R in all control and fructose-fed groups. CONCLUSION: Our results indicate that dietary selenium supplementation reduces microvascular dysfunction by increasing endothelial-dependent and independent dilatation and reducing macromolecular permeability increase in fructose-fed animals.

A Minimally Invasive Endoscopic Approach to Midcheek Mass: Showcase for Technical Description.

BACKGROUND: Surgical approaches to the midcheek area are challenging. This area is included between the lower eyelid above, and the upper lip below. The peculiar anatomical location makes it really important for attractiveness, thus the need to obtain a correct balance between the operation's safety and minimally invasive aspect. To the authors' knowledge, this is the first showcase and technical description of a novel minimally invasive endoscopic approach for midcheek mass removal. METHODS: Making 3 incisions in concealed area an endoscopically aided facial dissection was performed to remove a solitary venus malformation of the left midcheek region. RESULTS: After the surgical procedure was performed, no hematoma, no edema, or facial nerve paralysis were observed. To date, during the follow-up period, no recurrence of the lesion has been observed, and the quality of life of the patient was good with a minimally scar outcome. Magnetic resonance imaging, performed 2 weeks postoperatively, demonstrated a complete removal of the mass CONCLUSION:: The authors' finding experience suggests that the minimally invasive approach provides an excellent surgical window that achieves greater exposure for the dissection of the midcheek area. Further clinical applications are required to assess advantages and/or limitations of this procedure.

Surgical Resection of Vascular Lesions Involving the Buccal Fat Pad.

Vascular abnormalities are localized structural irregularities, which are performed during vasculogenesis, angiogenesis, and lymphangiogenesis. The involvement of soft tissue in such vascular malformations is frequent; however, the compromising of the buccal fat pads (Bichat bags) is uncommon, even in specialized centers, such as the plastic clinic of our institution, in which very few patients have been reported in the literature. The purpose of this article is to present a series of 2 patients in which vascular malformations involving the buccal fat pads, which were extracted by intraoral approach.

Regional heterogeneity in the mechanisms of myogenic tone in hamster arterioles.

Myogenic tone is an important feature of arterioles and resistance arteries, but the mechanisms responsible for this hallmark characteristic remain unclear. We used pharmacological inhibitors to compare the roles played by phospholipase C (PLC; 10 µM U73122), inositol 1,4,5-trisphosphate receptors (IP3Rs; 100 µM 2-aminoethoxydiphenylborane), protein kinase C (10 µM bisindolylmaleimide I), angiotensin II type 1 receptors (1 µM losartan), Rho kinase (10 nM-30 µM Y27632 or 300 nM H1152), stretch-activated ion channels (10 nM-1 µM Gd3+ or 5 µM spider venom toxin GsMTx-4) and L-type voltage-gated Ca2+ channels (0.3-100 µM diltiazem) in myogenic tone of cannulated, pressurized (80 cmH2O), second-order hamster cremaster or cheek pouch arterioles. Effective inhibition of either PLC or IP3Rs dilated cremaster arterioles, inhibited Ca2+ waves, and reduced global Ca2+ levels. In contrast, cheek pouch arterioles did not display Ca2+ waves and inhibition of PLC or IP3Rs had no effect on myogenic tone or intracellular Ca2+ levels. Inhibition of Rho kinase dilated both cheek pouch and cremaster arterioles with equal efficacy and potency but also reduced intracellular Ca2+ signals in both arterioles. Similarly, inhibition of mechanosensitive ion channels with Gd2+ or GsMTx-4 produced comparable dilation in both arterioles. Inhibition of L-type Ca2+ channels with diltiazem was more effective in dilating cremaster (86 ± 5% dilation, n = 4) than cheek pouch arterioles (54 ± 4% dilation, n = 6, P < 0.05). Thus, there are substantial differences in the mechanisms underlying myogenic tone in hamster cremaster and cheek pouch arterioles. Regional heterogeneity in myogenic mechanisms could provide new targets for drug development to improve regional blood flow in a tissue-specific manner.NEW & NOTEWORTHY Regional heterogeneity in the mechanisms of pressure-induced myogenic tone implies that resistance vessels may be able to alter myogenic signaling pathways to adapt to their environment. A better understanding of the spectrum of myogenic mechanisms could provide new targets to treat diseases that affect resistance artery and arteriolar function.

Computer-aided quantification of microvascular networks: Application to alterations due to pathological angiogenesis in the hamster.

Angiogenesis is both a physiological and a pathological process of great complexity, which is difficult to measure objectively and automatically. The hamster cheek pouch (HCP) prepared for intravital-microscopy (IVM) has been used to characterize microvascular functions in many studies and was chosen to investigate microvascular characteristics observed in normal non-infected hamsters as compared to those HCPs parasitized by Trypanosoma cruzi. Images of HCPs captured at IVM were subjected to computer based measurements of angiogenesis and histamine-induced macromolecular (FITC-dextran) leakage with an image segmentation approach that has the capacity to discriminate between fluorescence emitted by macromolecular tracers inside the vasculature and in the extravascular space. We present such an automatic segmentation methodology using known tools from image processing field that, to our knowledge, have not been tested in IVM images. We have compared this methodology with a recently published segmentation strategy based on image intensity thresholding. Our method renders an accurate and robust segmentation of blood vessels for different microvascular scenarios, normal and pathological. Application of the proposed strategy for objective and automatic measurement of angiogenesis detection was explored in detail.

Contribution of muscarinic receptors to in vitro and in vivo effects of Ruscus extract.

The objectives of this study were to evaluate, in vitro and in vivo, the contribution of muscarinic receptors to the effects of Ruscus extract. Ruscus extract was tested in competition binding experiments at recombinant human muscarinic receptors, heterologous expressed in Chinese Hamster Ovary (CHO) cells and in cellular assays measuring Ca2+ liberation and activator protein-1 (AP-1) reporter gene activation. The impact of muscarinic blockade on prolonged treatment outcome was evaluated using the hamster cheek pouch (HCP) microcirculation examining macromolecular permeability increase induced by histamine or ischemia/reperfusion (I/R), mean arteriolar and venular diameters, functional capillary density and I/R-induced leukocyte rolling and sticking. Ruscus extract exhibited affinities for muscarinic receptor subtypes at a range of 50-100µg/ml and behaved as partial agonist at human recombinant M1 and M3 receptors for Ca2+ liberation, confirmed in an AP-1 reporter gene assay. In the HCP model, topical application of atropine completely or partially blocked Ruscus extract-induced reductions of histamine- and I/R-induced increases of macromolecular permeability and leukocyte-endothelium interaction. Our results showed that Ruscus extract in vitro binds and activates different subtypes of muscarinic receptors and in vivo its anti-inflammatory effects are, at least partially, mediated via muscarinic receptors.

The Freestyle Facial Artery Perforator Flap for Reconstruction of Simultaneous Periorbital and Cheek Defects.

The reconstruction of defects involving the nasolabial, paranasal, and periorbital regions may be challenging, because they often involve more than one facial aesthetic unit, and can lead to functional problems. An average of 5 facial artery perforators of caliber >0.5 mm can be found above the mandible. A reference point for the location of the most constantly encountered perforator was suggested as being 1.5 cm lateral to the oral commissure, and at its same level in height or slightly inferior to the commissure. Based on injection studies, it is known that these perforators can supply an average area of 8 cm. The authors have extended the use of the freestyle perforator flap in a 87-year-old woman presented with an advanced melanoma of the paranasal area and nasolabial region (Breslow depth: 9 mm; Clark level V). Complete resection of the lesion with 3 cm oncological margins was performed. One-stage reconstruction with superior cosmetic results was achieved. The need for a perforator dissection is not necessarily a drawback, and classic concerns should be abandoned. The face is highly vascularized, and flap congestion is a rare event, usually a consequence of excessive pedicle trimming. Although technically more demanding, it should become one of the first reconstructive options when dealing with similar defects, if our results are confirmed in larger series.

Combined Intralesional Neodymium-Doped Yttrium Aluminium Garnet Laser and Intratumoral Ligation as Curative Treatment for Craniofacial Arteriovenous Malformations.

Craniofacial arteriovenous malformation (AVM), although very rare, has been a very difficult problem to treat especially when it is large and involves important structures. Surgical resection often results in unacceptable complications but still not curative. At our institution, treatment by combined intralesional neodymium-doped yttrium aluminium garnet laser and intratumoral ligation has been successful in venous malformation. This minimally invasive technique was then applied to more challenging AVM on the head and neck. Disease control was studied using clinical parameters and magnetic resonance imaging.Four patients with moderate-to-severe (Schobinger 2-4) craniofacial AVM were treated by this technique from 2001 to 2011. Patient age ranged from 2 to 51 years (mean: 25 years). After 2 to 4 treatments and follow-up period of 1456 days, 3 (75%) were cured. One of them was infant with huge mass and secondary pulmonary hypertension. Clinical cure was achieved after 3 treatments without residual cardiovascular compromise. The other patient (25%) had cheek mass with intraorbital involvement. The authors did not treat periorbital lesion so as to avoid triggering intraorbital spreading. The rest of the cheek lesion was clinically and radiologically cured.Laser energy setting, ablative technique, and skin cooling are the main factors determining the success. Individualized laser settings and properly set endpoints can increase treatment effectiveness in shorter period. In conclusion, this minimally invasive technique was successful in curing AVM without complication. With more clinical study and development of soft tissue monitoring tools, it is possible that intralesional laser could become the treatment of choice for all cutaneous AVM.

[Vascular anomaly in the midcheek region of an infant--review of the diagnostic procedure]. / Gefäßanomalie in der Wangenregion eines Säuglings - Diagnostischer Prozess anhand einer Kasuistik.

Clinical history, physical examination, evolution and imaging findings (Colour Doppler sonography, MRI if available) are of pivotal importance in the diagnostic pathway of an infantile vascular anomaly. Histopathology with specific stains and markers is contributive in difficult cases. Differentiation between vascular tumors (hemangioma) and vascular malformations is now well known and integrated into the ISSVA classification. We report here a 6-months-old boy, who presented with a localized cutaneous and expansive vascular birthmark in the left cheek and developed bleedings at the age of 18 months. Diagnostic features of a hemangioma were not evident, and the final diagnosis of a venous malformation was confirmed by histopathology.

Percutaneous Treatment of Large Venous Malformations in the Oral and Maxillofacial Regions Using Electrochemical Therapy Combined With Pingyangmycin.

PURPOSE: The aim of the present study was to evaluate the therapeutic outcome of using electrochemical therapy (ECT) combined with a sclerosing agent, pingyangmycin (bleomycin A5 hydrochloride; PYM), for large (>3 cm in diameter) venous malformations (VMs) in the oral and maxillofacial regions. PATIENTS AND METHODS: Thirty-five patients (15 male and 20 female; age range, 10 to 69 yr; mean age, 32 yr) with large VMs in the oral and maxillofacial region were treated with a combination of ECT and PYM under general anesthesia in the authors' department from June 2012 through May 2014. The size of the lesions varied from 3 × 3 to 12 × 15 cm. A repeated course of ECT and PYM was administered for larger VMs. The therapeutic interval was 3 months for ECT and 2 to 4 weeks for PYM. The dose of PYM for patients was 8 mg each time, and the injection concentration of PYM was 1.6 mg/mL. Patients were followed for 6 to 36 months. Therapeutic results were evaluated by clinical examination and Doppler ultrasonography before and after treatment. RESULTS: Of the 35 patients, 29 (82.9%) received 1 ECT treatment, 5 (14.3%) received 2 ECT treatments, and 1 (2.8%) received 3 ECT treatments. The number of PYM injection sessions was 1 to 5 (average, 2.5 times). According to the therapeutic criteria, the clinical outcome was excellent in 22 patients (62.9%), good in 10 patients (28.6%), and fair in 3 patients (8.5%). All patients (100%) had local swelling postoperatively that lasted approximately 1 to 2 weeks. Two patients (5.7%) had fever. No skin necrosis or nerve damage was found. CONCLUSIONS: Percutaneous treatment using ECT and PYM was a straightforward, safe, and reliable treatment modality for large VMs.

Aerobic exercise improves microvascular dysfunction in fructose fed hamsters.

Fructose is a major diet component directly related to severe damages to the microcirculation and to diseases such as obesity, diabetes and hypertension to which physical activity is pointed out as an important non-pharmacological treatment since its positive effects precede anthropometric improvements. In this study we have investigated the effects of a light/moderate aerobic exercise training (AET) on microcirculatory dysfunction elicited by carbohydrate overload during a period of 5 months. Male hamsters (Mesocricetus auratus) whose drinking water was substituted (F) or not (C) by 10% fructose solution, during 20 weeks, associated or not to AET in the last 4 weeks (EC and EF subgroups) had their microcirculatory function evaluated on the cheek pouch preparation, glucose and insulin tolerance (GTT and ITT) tested. Arterial blood was collected for pO2, pCO2, HCO3(-), pH, total CO2, saturated O2 and lactate determinations. Liver fragments were observed using an electron microscope. Microcirculatory responses to acetylcholine [Ach, an endothelium-dependent vasodilator; 10(-8)M - *123.3±7.5% (C), 119.5±1.3% (EC), *98.1±3.2% (F) and 133.6±17.2% (EF); 10(-6)M - *133.0±4.1% (C), 135.6±4.3% (EC), *103.4±4.3% (F) and 134.1±5.9% (EF); 10(-4)M - *167.2±5.0% (C), 162.8±5.4% (EC), *123.8±6.3% (F) and 140.8±5.0% (EF)] and to sodium nitroprusside [SNP, an endothelium-independent vasodilator; 10(-8)M - 118.8±6.8% (C), 114.0±5.0% (EC), 100.2±2.9% (F), 104.9±4.4% (EF); 10(-6)M - 140.6±11.7% (C), 141.7±5.5% (EC), 125.0±4.7% (F), 138.3±2.8% (EF); 10(-4)M - 150.4±10.9% (C), 147.9±6.5% (EC), 139.2±7.3% (F), 155.9±4.7% (EF)] and macromolecular permeability increase induced by 30 min ischemia/reperfusion (I/R) procedure [14.4±3.5 (C), 30.0±1.9 (EC), *112.0±8.8 (F) and *22.4±0.9 leaks/cm(2) (EF)] have shown that endothelium-dependent vasodilatation was significantly reduced and I/R induced macromolecular permeability augmented in sedentary fructose (F) subgroup and both improved after AET. Electron microscopy analysis of the liver showed significant differences between exercised and sedentary subgroups with greater amount of glycogen in F subgroups compared to other ones. No significant changes on mean arterial pressure, heart rate or blood gase between subgroups could be detected. Our results point out that AET could normalize microcirculatory dysfunction elicited by long term substitution of drinking water by 10% fructose solution.

The anatomical origin and course of the angular artery regarding its clinical implications.

BACKGROUND: The purposes of this study were to determine the morphological features and conceptualize the anatomical definition of the angular artery (AA) as an aid to practical operations in the clinical field. MATERIALS AND METHODS: Thirty-one hemifaces from 17 Korean cadavers and 26 hemifaces from 13 Thai cadavers were dissected. RESULTS: The topography of the AA was classified into 4 types according to its course: Type I (persistent pattern), in which the AA traverses the lateral side of the nose (11%); Type II (detouring pattern), in which the AA traverses the cheek and tear trough area (18%); Type III (alternative pattern), in which the AA traverses the medial canthal area through a branch of the ophthalmic artery (22.8%); and Type IV (latent pattern), in which the AA is absent (26.3%). CONCLUSION: The findings of this study will contribute toward improved outcomes for cosmetic surgery involving the injection of facial filler by enhancing the understanding of AA anatomy.

Arteriolar diameter and spontaneous vasomotion: importance of potassium channels and nitric oxide.

Arterioles display cyclic variations in diameter, termed vasomotion initiated by smooth muscle cells (SMCs), but the endothelium should also be evaluated due to its modulatory role on vessel tone. Since nitric oxide (NO) and prostacyclin (PGI2) regulate SMC tone and activate K(+) currents, we have investigated their role on vasomotion, by observing effects of topical application of N(ω)-nitro-l-arginine (L-NA, NO synthesis inhibitor), glibenclamide (KATP channel inhibitor), sodium nitroprusside (SNP, NO donor), iloprost (PGI2 analogue) and methylene blue (MB, cGMP production inhibitor) on the cheek pouch preparation of anesthetized male hamsters. L-NA (10(-10)-10(-6)M) induced vasoconstriction, reduction and abolition of vasomotion. MB (10(-7) to 10(-5)M) reduced mean arteriolar diameter with no changes on vasomotion. In the presence of 10(-6)M of MB, addition of 10(-6)L-NA totally abolished vasomotion without further constriction. Glibenclamide (10(-6)M) in the presence of L-NA at equimolar concentration restored both vasomotion frequency and amplitude. This effect was not observed in the presence of TEA 5mM. SNP (10(-10)-10(-6)M) induced a dose-dependent increase of arteriolar diameter and decreased vasomotion. Iloprost (10(-12)-10(-6)M) induced a concentration dependent increase of arteriolar diameter, reduced vasomotion frequency, but in lower concentrations (10(-12)-10(-10)M) increased its amplitude and in higher concentrations (10(-9)-10(-6)M) decreased it. SNP and iloprost inhibited vasomotion at 10(-7)M; however, at this concentration SNP and iloprost induced an increment of 35% and 50% of the initial arteriolar diameter, respectively. In the presence of L-NA (10(-6)M), vasomotion was restored by SNP at 10(-10)M and iloprost 10(-12)M, which corresponded to 80% of the initial diameter value. Around the initial (control) arteriolar diameter value, vasomotion presented its highest frequencies and amplitudes. Cessation of vasomotion occurred with L-NA (10(-6)M) in the presence of SNP (10(-6)M) and iloprost (10(-7)M) when arteriolar diameter reached 150% and 120% of its initial value, respectively. In conclusion, the present study strongly suggests that vasomotion (1) is not solely related to vascular tone, (2) needs an interplay between vascular tone and membrane currents and (3) could be modulated by NO (but not cGMP) and KATP channels. In addition, our results point to the existence of dissociation between vasomotion frequency and amplitude.

Reduced angiotensin II levels cause generalized vascular dysfunction via oxidant stress in hamster cheek pouch arterioles.

OBJECTIVES: We investigated the effect of suppressing plasma angiotensin II (ANG II) levels on arteriolar relaxation in the hamster cheek pouch. METHODS: Arteriolar diameters were measured via television microscopy during short-term (3-6days) high salt (HS; 4% NaCl) diet and angiotensin converting enzyme (ACE) inhibition with captopril (100mg/kg/day). RESULTS: ACE inhibition and/or HS diet eliminated endothelium-dependent arteriolar dilation to acetylcholine, endothelium-independent dilation to the NO donor sodium nitroprusside, the prostacyclin analogs carbacyclin and iloprost, and the KATP channel opener cromakalim; and eliminated arteriolar constriction during KATP channel blockade with glibenclamide. Scavenging of superoxide radicals and low dose ANG II infusion (25ng/kg/min, subcutaneous) reduced oxidant stress and restored arteriolar dilation in arterioles of HS-fed hamsters. Vasoconstriction to topically-applied ANG II was unaffected by HS diet while arteriolar responses to elevation of superfusion solution PO2 were unaffected (5% O2, 10% O2) or reduced (21% O2) by HS diet. CONCLUSIONS: These findings indicate that sustained exposure to low levels of circulating ANG II leads to widespread dysfunction in endothelium-dependent and independent vascular relaxation mechanisms in cheek pouch arterioles by increasing vascular oxidant stress, but does not potentiate O2- or ANG II-induced constriction of arterioles in the distal microcirculation of normotensive hamsters.

PaO2 oscillations caused by cyclic alveolar recruitment can be monitored in pig buccal mucosa microcirculation.

BACKGROUND: Cyclic alveolar recruitment and derecruitment play a role in the pathomechanism of acute lung injury and may lead to arterial partial pressure of oxygen (PaO(2) ) oscillations within the respiratory cycle. It remains unknown, however, if these PaO(2) oscillations are transmitted to the microcirculation. The present study investigates if PaO(2) oscillations can be detected in the pig buccal mucosa microcirculation. METHODS: Respiratory failure was induced by surfactant depletion in seven pigs. PaO(2) oscillations caused by cyclic recruitment and derecruitment were measured in the thoracic aorta by fast fluorescence quenching of oxygen technology. Haemoglobin oxygen saturation, haemoglobin amount and blood flow in the buccal mucosa microcirculation were determined by combined fast white light spectrometry and laser Doppler flowmetry additionally to systolic arterial pressure. Measurements were performed during baseline conditions and during cyclic recruitment and derecruitment. RESULTS: Measurements remained stable during baseline. Respiratory-dependent oscillations occurred in the systemic circulation [PaO(2) oscillations 92 (69-172) mmHg; systolic arterial pressure oscillations 33 (13-35) %] and were related to the respiratory rate (5.0 ± 0.2/min) as confirmed by Fourier analysis. Synchronised oscillations were detected to the pig buccal mucosa microcirculation [haemoglobin oxygen saturation oscillations 3.4 (2.7-4.9) %; haemoglobin amount oscillations 8.5 (2.3-13.3) %; blood flow oscillations 66 (18-87) %]. The delay between PaO(2) -\ and microcirculatory oxygen oscillations was 7.2 ± 2.8 s. CONCLUSION: The present study suggests that PaO(2) oscillations caused by cyclic recruitment and derecruitment were transmitted to the buccal mucosa microcirculation. This non-invasive approach of measuring oxygen waves as a surrogate parameter of cyclic recruitment and derecruitment could be used to monitor PaO(2) oscillations at the bedside.