COVID-19-associated encephalopathy with fulminant cerebral vasoconstriction: CT and MRI findings

Severe acute respiratory syndrome coronavirus 2 (SARS-Cov-2) can cause various mild to severe neurologic symptoms, leading to significant morbidity and mortality. We hereby present a fatal case of a 50-year-old male health care provider, admitted due to altered mental status due to encephalopathy, cerebral edema, and fulminant cerebral vasoconstriction caused by SARS-Cov-2. Our case highlights the importance of considering SARS-Cov-2 infection in the differential diagnosis for patients with unexplained central nervous system dysfunction and cerebral edema to prevent delayed diagnosis and render rapid treatment.

Light triggering goldsomes enable local NO-generation and alleviate pathological vasoconstriction

While nitric oxide (NO) can remedy vasoconstriction, inhalation of NO may cause systematic toxicity. We report a goldsome, which comprises a hollowed poly(lactic-co-glycolic acid) (PLGA) polymersome with S-nitrosoglutathione (GSNO, a NO donor) molecules and gold nanoparticles (Au NPs) incorporated in its hydrophilic core and hydrophobic membrane, respectively. Photothermal heating caused breakdown of polymersomes and enabled NO generation through reaction between GSNO and Au NPs. Photo-illumination at the zebrafish head led to local NO generation and selective cerebral vasodilation while it had little effects in regions away from the illumination site, and effectively mitigated hypoxia induced cerebral vasoconstriction. We demonstrate a translational potential by showing photo-stimulated NO generation with a clinical intravascular optical catheter. In conclusion, the goldsome, which enables light stimulated local NO generation and can be delivered with clinical intravascular optical catheters, should extend applications of NO therapies while surmounting limitations associated with systemic administration.

Hemorrhagic stroke associated with essential thrombocythemia: Case report and literature review

Hemorrhagic stroke associated with essential thrombocythemia (ET) is very infrequent. Herein, we report a case of a 33-year-old woman with a 2-year history of ET who developed intracerebral and subarachnoid hemorrhage. Angiography demonstrated severe vessel irregularity in the bilateral cerebral arteries. Molecular genetic testing revealed a calreticulin mutation. To our knowledge, hemorrhagic stroke has been reported in only six other patients with ET, and this is the first report of hemorrhagic stroke in an ET patient with a calreticulin mutation. We review the current literature and discuss the possible underlying mechanisms.

Body surface rewarming in fully and partially hypothermic king penguins

Penguins face a major thermal transition when returning to land in a hypothermic state after a foraging trip. Uninsulated appendages (flippers and feet) could provide flexible heat exchange during subsequent rewarming. Here, we tested the hypothesis that peripheral vasodilation could be delayed during this recovery stage. To this end, we designed an experiment to examine patterns of surface rewarming in fully hypothermic (the cloaca and peripheral regions (here; flippers, feet and the breast) < 37 °C) and partially hypothermic (cloaca at normothermia ≥ 37 °C, but periphery at hypothermia) king penguins (Aptenodytes patagonicus) when they rewarmed in the laboratory. Both groups rewarmed during the 21 min observation period, but the temperature changes were larger in fully than in partially hypothermic birds. Moreover, we observed a 5 min delay of peripheral temperature in fully compared to partially hypothermic birds, suggesting that this process was impacted by low internal temperature. To investigate whether our laboratory data were applicable to field conditions, we also recorded surface temperatures of free-ranging penguins after they came ashore to the colony. Initial surface temperatures were lower in these birds compared to in those that rewarmed in the laboratory, and changed less over a comparable period of time on land. This could be explained both by environmental conditions and possible handling-induced thermogenesis in the laboratory. Nevertheless, this study demonstrated that appendage vasodilation is flexibly used during rewarming and that recovery may be influenced by both internal temperature and environmental conditions when penguins transition from sea to land.

14-3-3ζ mediates an alternative, non-thermogenic mechanism in male mice to reduce heat loss and improve cold tolerance

Objective

Adaptive thermogenesis, which is partly mediated by sympathetic input on brown adipose tissue (BAT), is a mechanism of heat production that confers protection against prolonged cold exposure. Various endogenous stimuli, for example, norepinephrine and FGF-21, can also promote the conversion of inguinal white adipocytes to beige adipocytes, which may represent a secondary cell type that contributes to adaptive thermogenesis. We previously identified an essential role of the molecular scaffold 14-3-3ζ in adipogenesis, but one of the earliest, identified functions of 14-3-3ζ is its regulatory effects on the activity of tyrosine hydroxylase, the rate-limiting enzyme in the synthesis of norepinephrine. Herein, we examined whether 14-3-3ζ could influence adaptive thermogenesis via actions on BAT activation or the beiging of white adipocytes.

Methods

Transgenic mice over-expressing a TAP-tagged human 14-3-3ζ molecule or heterozygous mice without one allele of Ywhaz, the gene encoding 14-3-3ζ, were used to explore the contribution of 14-3-3ζ to acute (3 h) and prolonged (3 days) cold (4 °C) exposure. Metabolic caging experiments, PET-CT imaging, and laser Doppler imaging were used to determine the effect of 14-3-3ζ over-expression on thermogenic and vasoconstrictive mechanisms in response to cold.

Results

Transgenic over-expression of 14-3-3ζ (TAP) in male mice significantly improved tolerance to acute and prolonged cold. In response to cold, body temperatures in TAP mice did not decrease to the same extent when compared to wildtype (WT) mice, and this was associated with increased UCP1 expression in beige inguinal white tissue (iWAT) and BAT. Of note was the paradoxical finding that cold-induced changes in body temperatures of TAP mice were associated with significantly decreased energy expenditure. The marked improvements in tolerance to prolonged cold were not due to changes in sensitivity to β-adrenergic stimulation or BAT or iWAT oxidative metabolism; instead, over-expression of 14-3-3ζ significantly decreased thermal conductance and heat loss in mice via increased peripheral vasoconstriction.

Conclusions

Despite being associated with elevations in cold-induced UCP1 expression in brown or beige adipocytes, these findings suggest that 14-3-3ζ regulates an alternative, non-thermogenic mechanism via vasoconstriction to minimize heat loss during cold exposure.

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14-3-3ζ over-expression in male mice improves tolerance to acute and prolonged cold.

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Increasing 14-3-3ζ expression promotes beiging of inguinal white adipose tissue.

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Cold-induced changes in body temperature can be dissociated from energy expenditure.

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14-3-3ζ-dependent decreases in heat loss are associated with vasoconstriction.

Estrogen increases expression of vascular alpha 2C adrenoceptor through the cAMP/Epac/JNK/AP-1 pathway and potentiates cold-induced vasoconstriction

Cutaneous cold-induced vasoconstriction is a normal physiological reaction mediated by alpha 2C-adrenergic receptors (α_2C-ARs) expressed in vascular smooth muscle cells (VSMCs). When this reaction is exaggerated, Raynaud's phenomenon (RP) ensues. RP is more prevalent in females compared to age-matched men. We previously established that 17-β estradiol (estrogen) upregulates α_2C-ARs in human VSMCs via a cAMP/Epac/Rap pathway. We also showed that cAMP acts through JNK to increase α_2C-AR expression. However, whether estrogen employs JNK to regulate α_2C-AR is not investigated. Knowing that the α_2C-AR promoter harbors an activator protein-1 (AP-1) binding site that can be potentially activated by JNK, we hypothesized that estrogen regulates α_2C-AR expression through an Epac/JNK/AP-1 pathway. Our results show that estrogen (10^-10 M) activated JNK in human VSMCs extracted from cutaneous arterioles. Pretreatment with ESI09 (10 μM; an Epac inhibitor), abolished estrogen-induced JNK activation. In addition, pre-treatment with SP600125 (3 μM; a JNK specific inhibitor) abolished estrogen-induced expression of α_2C-AR. Importantly, estrogen-induced activation of α_2C-AR promoter was attenuated with SP600125. Moreover, transient transfection of VSMCs with an Epac dominant negative mutant (Epac-DN) abolished estrogen-induced activation of α_2C-AR promoter. However, co-transfection of constitutively active JNK mutant overrode the inhibitory effect of Epac-DN on α_2C-AR promoter. Moreover, estrogen caused a concentration-dependent increase in the activity of AP-1-driven reporter construct. Mutation of AP-1 site in the α_2C-AR promoter abolished its activation by estrogen. This in vitro estrogen-increased α_2C-AR expression was mirrored by an increase in the ex vivo functional responsiveness of arterioles. Indeed, estrogen potentiated α_2C-AR-mediated cold-induced vasoconstriction, which was abolished by SP600125. Collectively, these results indicate that estrogen upregulates α_2C-AR expression via an EPAC-mediated JNK/AP-1- dependent mechanism. These results provide an insight into the mechanism by which exaggerated cold-induced vasoconstriction occurs in estrogen-replete females and identify Epac and JNK as potential targets for the treatment of RP.

Non-surgical management of methamphetamine induced testicular ischemia

A rare case of methamphetamine induced testicular ischemia, a 35-year-old man with clinical and sonographic features of left epididymitis. However, Ultrasound incidentally showed a lack of vascularity of the right testicle despite being asymptomatic on the right hemi-scrotum. He was a known intravenous methamphetamine user, admitting his last injection was 4 h prior to his presentation.

The left epididymitis was treated with antibiotics, analgesia and scrotal support, while right testicle was treated conservatively with serial ultrasounds. Repeat ultrasound in 20 h confirmed the return of normal vascularity of the right testicle confirming methamphetamine induced testicular ischemia, no surgical intervention needed.

Autonomically-mediated decrease in microvascular blood flow due to mental stress and pain in sickle cell disease: A target for neuromodulatory interventions

Pain and vaso-occlusive crises (VOC) are hallmark complications of sickle cell disease (SCD) and result in significant physical and psychosocial impairment. The variability in SCD pain frequency and triggers for the transition from steady state to VOC are not well understood. This paper summarizes the harmful physiological effects of pain and emotional stressors on autonomically-mediated vascular function in individuals with SCD and the effects of a cognitive, neuromodulatory intervention (i.e. hypnosis) on microvascular blood flow. We reviewed recent studies from the authors' vascular physiology laboratory that assessed microvascular responses to laboratory stressors in individuals with SCD. Results indicate that participants with SCD exhibit marked neurally mediated vascular reactivity in response to pain, pain-related fear, and mental stress. Further, pilot study results show that engagement in hypnosis may attenuate harmful microvascular responses to pain. The collective results demonstrate that autonomically-mediated vascular responses to pain and mental stress represent an important SCD intervention target. This ongoing work provides physiological justification for the inclusion of cognitive, neuromodulatory and complementary treatments in SCD disease management and may inform the development of targeted, integrative interventions that prevent the enhancement of autonomic vascular dysfunction in SCD.

Effect of vasopressin as a local anesthetic in mice

We sought to elucidate how the local administration of mepivacaine hydrochloride and vasopressin via the tail affects the peripheral blood flow volume, tissue dynamics, and mepivacaine's anesthetic effect in mice. Two-hundred and twenty-six male ICR mice were used in this study. Blood flow was measured after administering mepivacaine alone or mepivacaine with either 0.03, 0.3, or 3.0 U/mL vasopressin or 10 µg/mL epinephrine via the tail tissue. The tail tissue and blood dynamics were measured using ³H-labeled mepivacaine hydrochloride with vasopressin or epinephrine. The compound nerve action potential (CNAP) was measured to clarify the anesthetic effect after administering mepivacaine with 0.3 U/mL vasopressin. The statistical methods employed were Steel-Dwass test, Mann-Whitney U test, Dunnett's test, and Tukey test. P < 0.05 indicated statistical significance. The results revealed that the local administration of ≥ 0.03 U/mL vasopressin reduced local blood flow and prolonged ³H-M localization in the tail tissue in a concentration-dependent manner. Addition of 0.3 U/mL vasopressin enhanced and prolonged the anesthetic effect of mepivacaine. The findings suggest that adding vasopressin to a local anesthetic regimen may be effective, and thus it could be applied as a vasoconstrictor.

Mechanisms underlying the vascular relaxation activities of Zingiber officinale var. rubrum in thoracic aorta of spontaneously hypertensive rats

OBJECTIVE

To evaluate vasorelaxant and vasoconstriction effects of Zingiber officinale var. rubrum (ZOVR) on live rats and isolated aortic rings of spontaneously hypertensive rats (SHRs).

METHODS

Extracts of ZOVR were subjected to in-vivo antihypertensive screening using noninvasive blood pressures in SHRs. The most potent extract, ZOVR petroleum ether extract (ZOP) was then fractionated using n-hexane, chloroform and water. Isolated thoracic aortic rings were harvested and subjected to vascular relaxation studies of n-hexane fraction of ZOP (HFZOP) with incubation of different antagonists such as Nω-nitro-l-arginine methyl ester (L-NAME, 10 µmol/L), indomethacin (10 µmol/L), methylene blue (10 µmol/L), atropine (1 µmol/L), glibenclamide (10 µmol/L), prazosin (0.01 µmol/L), and propranolol (1 µmol/L).

RESULTS

During the screening of various ZOVR extracts, ZOP produced the most reduction in blood pressures of SHRs and so did HFZOP. HFZOP significantly decreased phenylephrine-induced contraction and enhanced acetylcholine-induced relaxation. L-NAME, indomethacin, methylene blue, atropine, and glibenclamide significantly potentiated the vasorelaxant effects of HFZOP. Propranolol and prazosin did not alter the vasorelaxant effects of HFZOP. HFZOP significantly suppressed the Ca2+-dependent contraction and influenced the ratio of the responses to phenylephrine in Ca2+-free medium.

CONCLUSION

This study demonstrates that ZOP may exert an antihypertensive effect in the SHR model. Its possible vascular relaxation mechanisms involve nitric oxide and prostacyclin release, activation of cGMP-KATP channels, stimulation of muscarinic receptors, and transmembrane calcium channel or Ca2+ release from intracellular stores. Possible active compounds that contribute to the vasorelaxant effects are 6-gingerol, 8-gingerol and 6-shogaol.

Evaluating the thermal protection provided by a 2‒3 mm wet suit during fin diving in shallow water with a temperature of 16‒20°C

INTRODUCTION

The purpose of the study was to evaluate the thermal protection provided by a 2-3 mm surfing wet suit during at least two hours of fin diving in shallow water with a temperature of 16-20°C. We examined the effect of wearing the suit while diving in cold water on cognitive performance, muscle strength, and hand motor function.

METHODS

Subjects were six male well-trained rebreather divers, 19-23 years old, acclimatised to cold. They attended the laboratory on three separate occasions, when we conducted the experiment at one of three temperatures, 16, 18, and 20°C. Core temperature (gastrointestinal system), skin temperature, oxygen consumption, and cold perception were evaluated during the test. Before and immediately after the dives, subjects performed a series of cognitive, manual dexterity, and muscle strength tests.

RESULTS

Core temperature decreased by 0.35-0.81°C over the two hours at all three water temperatures. No subject reached a core temperature below 35°C. The decrease in upper body skin temperature during the two hour dive ranged between 5.97 and 8.41°C (P < 0.05). Two hours diving in 16-20°C water resulted in a significant increase in the time taken to perform the task of unlinking and reassembling four shackles (∼30% longer, P < 0.05). No effect was found on the cognitive or muscle strength tests.

CONCLUSIONS

A 2-3 mm wet suit provides adequate thermal protection in trained and cold-acclimatised young males engaged in active diving in shallow water with a temperature of 16°C and above.

The hypertensive potential of estrogen: An untold story

Cardiovascular disease (CVD) is the major cause of morbidity and mortality worldwide. The implication of estrogen in this disease has been extensively studied. While the vast majority of published research argue for a cardioprotective role of estrogen in vascular inflammation such as in atherosclerosis, the role of estrogen in hypertension remains far from being resolved. The vasorelaxant effect of estrogen has already been well-established. However, emerging evidence supports a vasoconstrictive potential of this hormone. It has been proposed that the microenvironment dictates the effect of estrogen-induced type 1 nitric oxide synthase-1 (nNOS) on vasotone. Indeed, depending on nNOS product, nitric oxide or superoxide, estrogen can induce vasodilation or vasoconstriction, respectively. In this review, we discuss the evidence supporting the vasorelaxant effects of estrogen, and the molecular players involved. Furthermore, we shed light on recent reports revealing a vasoconstrictive role of estrogen, and speculate on the underlying signaling pathways. In addition, we identify certain factors that can account for the discrepant estrogenic effects. This review emphasizes a yin-yang role of estrogen in regulating blood pressure.

A Histological Study of Vasoconstriction by Local Anesthetics in Mandible

To assess the effect of epinephrine-containing local anesthetics on vasoconstriction, we immunohistochemically measured the intravascular lumen area in different regions of the mandible. Twelve male Wistar rats were used. General anesthesia was induced and maintained with sevoflurane. Infiltration anesthesia was performed with 0.2 mL of epinephrine-free 2% lidocaine (E-) near the left mandibular first molar and with 0.2 mL of epinephrine-containing 2% lidocaine (E+) near the right mandibular first molar. After decalcification, the specimens were paraffinized, and thin sections were prepared and immunohistologically stained with an antismooth muscle actin antibody. The intravascular lumen area was measured in the mucosa, periodontal membrane, Haversian/Volkmann's canal, and bone marrow. A Mann-Whitney U test was used for statistical processing, and p < .05 was considered to indicate a statistically significant difference. In the oral mucosa and the periodontal membrane, E+ had a significantly smaller vascular lumen area than E-. In the Haversian/Volkmann's canal and the bone marrow, no significant intergroup difference was observed in the intravascular lumen area. We postulate that this is due to a low smooth muscle content of blood vessels in the mandible and suggest that the vasoconstrictive effect of epinephrine-containing local anesthetics within the mandible is ineffective.

Carbon monoxide attenuates vasospasm and improves neurobehavioral function after subarachnoid hemorrhage

Subarachnoid hemorrhage (SAH) is a devastating form of hemorrhagic stroke and is a serious medical condition caused by bleeding usually due to a ruptured aneurysm. Oxidative stress and inflammation from hemoglobin and heme released from lysed red blood cells are some postulated causes of vasospasm during SAH, which could lead to delayed cerebral ischemia. At low amounts, carbon monoxide (CO) gas may be neuroprotective through anti-inflammation, anti-cell death, and restoration of normal blood flow. Hence, this study focuses on a noninvasive strategy to treat SAH by using CO as a therapeutic medical gas. Mice were treated with 250 ppm CO or air for 1h started at 2h after SAH. Various anatomical and functional outcomes were monitored at 1 and 7d after SAH. CO decreased neurological deficit score (47.4 ± 10.5%) and increased activity (30.0 ± 9.1%) and stereotypic counts (261.5 ± 62.1%) at 7d. There was a significant increase in lumen area/wall thickness ratio in the middle cerebral artery (173.5 ± 19.3%), which tended to increase in the anterior cerebral artery (25.5 ± 4.3%) at 7d. This is the first report to demonstrate that CO minimizes delayed SAH-induced neurobehavioral deficits, which suggests that post-treatment with CO gas or CO-donors can be further tested as a potential therapy against SAH.

Raynaud's phenomenon manifesting as progressive abnormal MRI bone marrow signal in the toes

Objective

The purpose of this report is to discuss the presentation and the progressive magnetic resonance imaging (MRI) findings in a single patient with clinically-diagnosed Raynaud's phenomenon (RP).

Conclusion

RP can present as non-specific toe pain and manifest as progressive abnormal MRI bone marrow signal in the toes. In addition to patient presentation and clinical assessment, this information could contribute to earlier diagnosis and treatment of RP and other coexisting rheumatologic disorders.

Dissecting genetic factors affecting phenylephrine infusion rates during anesthesia: a genome-wide association study employing EHR data

BACKGROUND

The alpha-adrenergic agonist phenylephrine is often used to treat hypotension during anesthesia. In clinical situations, low blood pressure may require prompt intervention by intravenous bolus or infusion. Differences in responsiveness to phenylephrine treatment are commonly observed in clinical practice. Candidate gene studies indicate genetic variants may contribute to this variable response.

METHODS

Pharmacological and physiological data were retrospectively extracted from routine clinical anesthetic records. Response to phenylephrine boluses could not be reliably assessed, so infusion rates were used for analysis. Unsupervised k-means clustering was conducted on clean data containing 4130 patients based on phenylephrine infusion rate and blood pressure parameters, to identify potential phenotypic subtypes. Genome-wide association studies (GWAS) were performed against average infusion rates in two cohorts: phase I (n = 1205) and phase II (n = 329). Top genetic variants identified from the meta-analysis were further examined to see if they could differentiate subgroups identified by k-means clustering.

RESULTS

Three subgroups of patients with different response to phenylephrine were clustered and characterized: resistant (high infusion rate yet low mean systolic blood pressure (SBP)), intermediate (low infusion rate and low SBP), and sensitive (low infusion rate with high SBP). Differences among clusters were tabulated to assess for possible confounding influences. Comorbidity hierarchical clustering showed the resistant group had a higher prevalence of confounding factors than the intermediate and sensitive groups although overall prevalence is below 6%. Three loci with P < 1 × 10^-6 were associated with phenylephrine infusion rate. Only rs11572377 with P = 6.09 × 10^-7, a 3'UTR variant of EDN2, encoding a secretory vasoconstricting peptide, could significantly differentiate resistant from sensitive groups (P = 0.015 and 0.018 for phase I and phase II) or resistant from pooled sensitive and intermediate groups (P = 0.047 and 0.018).

CONCLUSIONS

Retrospective analysis of electronic anesthetic records data coupled with the genetic data identified genetic variants contributing to variable sensitivity to phenylephrine infusion during anesthesia. Although the identified top gene, EDN2, has robust biological relevance to vasoconstriction by binding to endothelin type A (ET_A) receptors on arterial smooth muscle cells, further functional as well as replication studies are necessary to confirm this association.

Differential effects of saturated and unsaturated fatty acids on vascular reactivity in isolated mesenteric and femoral arteries of rats

Free fatty acid (FFA) intake regulates blood pressure and vascular reactivity but its direct effect on contractility of systemic arteries is not well understood. We investigated the effects of saturated fatty acid (SFA, palmitic acid), polyunsaturated fatty acid (PUFA, linoleic acid), and monounsaturated fatty acid (MUFA, oleic acid) on the contractility of isolated mesenteric (MA) and deep femoral arteries (DFA) of Sprague-Dawley rats. Isolated MA and DFA were mounted on a dual wire myograph and phenylephrine (PhE, 1-10 µM) concentration-dependent contraction was obtained with or without FFAs. Incubation with 100 µM of palmitic acid significantly increased PhE-induced contraction in both arteries. In MA, treatment with 100 µM of linoleic acid decreased 1 µM PhE-induced contraction while increasing the response to higher PhE concentrations. In DFA, linoleic acid slightly decreased PhE-induced contraction while 200 µM oleic acid significantly decreased it. In MA, oleic acid reduced contraction at low PhE concentration (1 and 2 µM) while increasing it at 10 µM PhE. Perplexingly, depolarization by 40 mM KCl-induced contraction of MA was commonly enhanced by the three fatty acids. The 40 mM KCl-contraction of DFA was also augmented by linoleic and oleic acids while not affected by palmitic acid. SFA persistently increased alpha-adrenergic contraction of systemic arteries whereas PUFA and MUFA attenuated PhE-induced contraction of skeletal arteries. PUFA and MUFA concentration-dependent dual effects on MA suggest differential mechanisms depending on the types of arteries. Further studies are needed to elucidate underlying mechanisms of the various effects of FFA on systemic arteries.

Methylation-reprogrammed AGTR1 results in increased vasoconstriction by angiotensin II in human umbilical cord vessel following in vitro fertilization-embryo transfer

AIMS

Assisted reproductive technologies (ART) have been widely used to treat infertility, which may impact on fetuses and offspring. This study investigated the effects of in vitro fertilization-embryo transfer (IVF-ET) on angiotensin II (AII)-mediated vasoconstrictions in umbilical cord vein, and explored possible reprogrammed methylation mechanism.

MATERIALS AND METHODS

Human umbilical cords were randomly divided into ordinary pregnancy and IVF-ET pregnancy. Vascular studies with AII as well as its specific receptor antagonists losartan and PD123,319 were conducted. Real-time quantitative PCR, Western blotting, and methylation analysis by bisulfite sequencing were performed with the cord vessel samples.

KEY FINDINGS

In IVF-ET group, the maximal response to AII in umbilical vessels was significantly greater than that in the ordinary pregnancy. Using losartan and PD123,319, angiotensin receptor subtype 1 (AT1R) was found mainly responsible for the enhanced contraction in the umbilical vein of IVF-ET pregnancy. Decreased mRNA expression of DNMT3A was found in umbilical vein of IVF-ET group. Hypomethylation of the AGTR1 gene (gene encoding AT1R) in the umbilical veins of the IVF group was found. The data suggested that the IVF-ET treatments altered AII-mediated vasoconstrictions in umbilical veins, which could be partially attributed to the increased expression of AT1R.

SIGNIFICANCE

The hypo-methylation of the AGTR1 gene caused by IVF-ET might play important roles in altered vasoconstrictions, impacting on cardiovascular systems in the long run.

Ca2+ Signalling in Pericytes

Microcirculation is the generic name for the finest level of the circulatory system and consists of arteriolar and venular networks located upstream and downstream of capillaries, respectively. Anatomically arterioles are surrounded by a monolayer of spindle-shaped smooth muscle cells (myocytes), while terminal branches of precapillary arterioles, capillaries and all sections of postcapillary venules are surrounded by a monolayer of morphologically different perivascular cells (pericytes). Pericytes are essential components of the microvascular vessel wall. Wrapped around endothelial cells, they occupy a strategic position at the interface between the circulating blood and the interstitial space. There are physiological differences in the responses of pericytes and myocytes to vasoactive molecules, which suggest that these two types of vascular cells could have different functional roles in the regulation of local blood flow within the same microvascular bed. Also, pericytes may play different roles in different microcirculatory beds to meet the characteristics of individual organs. Contractile activity of pericytes and myocytes is controlled by changes of cytosolic free Ca²⁺concentration. In this chapter, we attempt to summarize the results in the field of Ca²⁺ signalling in pericytes especially in light of their contractile roles in different tissues and organs. We investigate the literature and describe our results regarding sources of Ca²⁺, relative importance and mechanisms of Ca²⁺ release and Ca²⁺ entry in control of the spatio-temporal characteristics of the Ca²⁺ signals in pericytes, where possible Ca²⁺ signalling and contractile responses in pericytes are compared to those of myocytes.

Benzo[a]pyrene alters vascular function in rat aortas ex vivo and in vivo

Benzo[a]pyrene (BaP) is a polycyclic aromatic hydrocarbon found in tobacco smoke and air pollution products. BaP exposure has been recently suggested to be a risk factor for hypertension in coke oven workers. The mechanisms of BaP on vascular smooth muscle function remain unclear. Here, we examined the influence and possible mechanism of BaP on vasoconstriction in rat thoracic aortas ex vivo and in vivo. In vivo exposure of rats to BaP (20 mg/kg) for 8 weeks caused a significant enhancement in the systolic blood pressure and enhanced aortic hyperreactivity to α1-adrenoceptor selective agonist phenylephrine in aortas. BaP (1 and 10 μM) treatment for 18 h induced an enhancement of phenylephrine-induced vasoconstriction in the organ cultures of aortas. Aryl hydrocarbon receptor antagonist α-naphthoflavone, protein kinase C (PKC) inhibitor chelerythrine, mitogen-activated protein kinases (MAPK) inhibitor PD98059, myosin light chain kinase (MLCK) inhibitor ML-9, and Rho-kinase inhibitor Y-27632 significantly suppressed BaP-enhanced vasoconstriction. BaP time-dependently triggered reactive oxygen species (ROS) production in primary vascular smooth muscle cells. Both antioxidant N-acetylcysteine and NAD(P)H oxidase inhibitor diphenyleneiodonium significantly inhibited BaP-triggered ROS production and vasoconstriction. These results suggest that BaP enhances aortic vasoconstriction via the activation of ROS and muscular signaling molecules PKC, MAPK, MLCK, and Rho-kinase.

Vasoconstrictor component of atherothrombotic culprit lesions in ST-segment elevation myocardial infarction

OBJECTIVE

The vasoconstrictor component of atherothrombotic culprit lesions in ST-elevation myocardial infarction (STEMI) patients has not been fully investigated. This study was aimed at assessing the vasoconstrictor component of atherothrombotic culprit lesions in patients with STEMI receiving primary percutaneous coronary intervention (PCI).

METHODS

A group of 100 patients with STEMI were enrolled prospectively. Baseline coronary angiography achieving normal antegrade flow was followed by 200 μg of intracoronary nitroglycerin (NTG) injection and repeat coronary angiography at the same projection view for culprit lesions was performed. End points were the changes in lesion length, reference vessel diameter, minimal lumen diameter, and diameter stenosis by quantitative coronary analysis before and after NTG injection.

RESULTS

Reference vessel diameter (2.7 ± 0.5 mm vs. 2.9 ± 0.5 mm, p < 0.001) and minimal lumen diameter (0.9 ± 0.4 mm vs. 1.2 ± 0.5 mm, p < 0.001) increased after NTG injection, whereas lesion length (24.1 ± 7.4 mm vs. 23.4 ± 7.6 mm, p = 0.001) and diameter stenosis (66.6 ± 14.8% vs. 58.3 ± 16.1%, p < 0.001) decreased. The median percentage change of diameter stenosis was -4.0% (Interquartile range: -13.8% to -1.0%), which was used as the cut-off value to divide the cohort into NTG responder or nonresponder groups accordingly. Total stent length was significantly shorter in the responder group compared with the nonresponder group (27.4 ± 11.6 mm vs. 33.7 ± 16.8 mm, p = 0.042).

CONCLUSION

This study showed the presence of a vasoconstrictor component in atherothrombotic culprit lesions in STEMI patients receiving primary PCI. Vasodilating effort by NTG may decrease stent length used for culprit lesions.

Marsdenia tenacissima extract dilated small mesenteric arteries via stimulating endothelial nitric oxide synthase and inhibiting calcium influx

ETHNOPHARMACOLOGICAL RELEVANCE

Marsdenia tenacissima is a traditional Chinese medicine that is known to be effective in combating cancer as well as reducing blood pressure. The efficacy and mechanisms of Marsdenia tenacissima in treating cancer have been well described. However, the potential vasoactivities of Marsdenia tenacissima remain poorly known.

AIM OF THE STUDY

To determine the vasoactive effects of the water-soluble part of marsdenia tenacissima in mesenteric resistance arteries of the mice, and to explore the underlying mechanisms.

MATERIALS AND METHODS

Isometric vessel tension study was used to examine the effects of marsdenia tenacissima extract (MTE) on vasodilation of the mesenteric arteries of mice. KCl, phenylephrine (PE) and 9,11-Dideoxy-11α,9α-epoxymethanoprostaglandin F2α (U46619) were used as vasoconstrictors. Y27632, Nitro-L-arginine methyl ester hydrochloride (L-NAME) and indomethacin were used to explore the underlying mechanisms for the vasoactivities of MTE. Western blot and nitric oxide (NO) assay were used to evaluate the effects of MTE on the activities of endothelial nitric oxide synthase (eNOS).

RESULTS

MTE (5-50 mg/mL), but not vehicle, dose-dependently relaxed the mesenteric arteries constricted with KCl, PE or U46619, in which relaxations to KCl were more pronounced than that to PE or U46619. Pre-incubation of the vessels with MTE (40 mg/mL) reduced the vasoconstrictions caused by calcium influx. Decreasing calcium sensitivity by inhibition of Rho kinase (ROCK) significantly augmented the vasorelaxation of MTE. While, inhibition of endothelial cells by pre-incubation with L-NAME (300 μM) and indomethacin (10 μM) or denudating endothelial cells attenuated vasorelaxations of MTE to KCl, and with a larger potency, to U46619. In both human umbilical vein endothelial cells (HUVECs) and human heart microvascular endothelial cells (HMECs), the phosphorylations of eNOS and the production of NO were significantly enhanced after treatment of MTE for 2, 5, 10, 30 min.

CONCLUSIONS

MTE, the water-soluble part of marsdenia tenacissima, was effective in relaxing mesenteric resistance arteries via inhibiting calcium influx and stimulating eNOS activities.

Inhaled nitric oxide prevents systemic and pulmonary vasoconstriction due to hemoglobin-based oxygen carrier infusion: A case report

Hemoglobin-based oxygen carriers (HBOCs) are used in extreme circumstances to increase hemoglobin concentration and improve oxygen delivery when allogenic red blood cell transfusions are contraindicated or not immediately available. However, HBOC-induced severe pulmonary and systemic vasoconstriction due to peripheral nitric oxide (NO) scavenging has stalled its implementation in clinical practice. We present a case of an 87 year-old patient with acute life-threatening anemia who received HBOC while breathing NO gas. This case shows that inhaled NO allows for the safe use of HBOC infusion by preventing HBOC-induced pulmonary and systemic vasoconstriction.

High Sodium Intake Impairs Small Artery Vasoreactivity in vivo in Dahl Salt-Sensitive Rats

The effects of high sodium intake on the functionality of resistance arteries have been repeatedly studied in vitro, but no study has focused on salt-sensitive hypertension in vivo. We studied the in vivo reactivity of mesenteric small arteries (MSAs) to vasoactive agents in Dahl salt-sensitive (DS) rats with various sodium diets. Twenty-four male DS rats were randomized into 3 groups: LS (0.3% NaCl diet), NS (0.6% NaCl diet), and HS (8% NaCl diet). After a 12-week intervention, the diameter changes of the MSAs after noradrenaline (NA) and acetylcholine (ACh) exposure were detected by a microscope, and changes in blood perfusion through the MSAs were measured by full-field laser perfusion imaging. HS enhanced the constrictive response of the MSAs to NA and attenuated the relaxing response to ACh. Low sodium intake reduced the response of the MSAs to NA and promoted ACh-induced vasodilatation. HS also aggravated NA-induced blood perfusion reduction and impaired ACh-induced hyperperfusion of the MSAs. Pathologically, HS was associated with arteriolar structural damage and fibrosis of the MSAs. We conclude that sodium intake affects the responsiveness of the MSAs to vasoactive agents in DS rats and might play important roles in modulating blood pressure in hypertensive individuals.