Dilation of Pregnant Rat Uterine Arteries with Phenols from Extra Virgin Olive Oil Is Endothelium-Dependent and Involves Calcium and Potassium Channels.

During pregnancy, uterine vasculature undergoes significant circumferential growth to increase uterine blood flow, vital for the growing feto-placental unit. However, this process is often compromised in conditions like maternal high blood pressure, particularly in preeclampsia (PE), leading to fetal growth impairment. Currently, there is no cure for PE, partly due to the adverse effects of anti-hypertensive drugs on maternal and fetal health. This study aimed to investigate the vasodilator effect of extra virgin olive oil (EVOO) phenols on the reproductive vasculature, potentially benefiting both mother and fetus. Isolated uterine arteries (UAs) from pregnant rats were tested with EVOO phenols in a pressurized myograph. To elucidate the underlying mechanisms, additional experiments were conducted with specific inhibitors: L-NAME/L-NNA (10-4 M) for nitric oxide synthases, ODQ (10-5 M) for guanylate cyclase, Verapamil (10-5 M) for the L-type calcium channel, Ryanodine (10-5 M) + 2-APB (3 × 10-5 M) for ryanodine and the inositol triphosphate receptors, respectively, and Paxilline (10-5 M) for the large-conductance calcium-activated potassium channel. The results indicated that EVOO-phenols activate Ca2+ signaling pathways, generating nitric oxide, inducing vasodilation via cGMP and BKCa2+ signals in smooth muscle cells. This study suggests the potential use of EVOO phenols to prevent utero-placental blood flow restriction, offering a promising avenue for managing PE.

G-Protein-Coupled Estrogen Receptor Expression in Rat Uterine Artery Is Increased by Pregnancy and Induces Dilation in a Ca2+ and ERK1/2 Dependent Manner.

Increasing levels of estrogens across gestation are partly responsible for the physiological adaptations of the maternal vasculature to pregnancy. The G protein-coupled estrogen receptor (GPER) mediates acute vasorelaxing effects in the uterine vasculature, which may contribute to the regulation of uteroplacental blood flow. The aim of this study was to investigate whether GPER expression and vasorelaxation may occur following pregnancy. Elucidation of the functional signalling involved was also investigated. Radial uterine and third-order mesenteric arteries were isolated from non-pregnant (NP) and pregnant rats (P). GPER mRNA levels were determined and-concentration-response curve to the GPER-specific agonist, G1 (10-10-10-6 M), was assessed in arteries pre-constricted with phenylephrine. In uterine arteries, GPER mRNA expression was significantly increased and vasorelaxation to G1 was significantly enhanced in P compared with NP rats. Meanwhile, in mesenteric arteries, there was a similar order of magnitude in NP and P rats. Inhibition of L-type calcium channels and extracellular signal-regulated kinases 1/2 significantly reduced vasorelaxation triggered by G1 in uterine arteries. Increased GPER expression and GPER-mediated vasorelaxation are associated with the advancement of gestation in uterine arteries. The modulation of GPER is exclusive to uterine arteries, thus suggesting a physiological contribution of GPER toward the regulation of uteroplacental blood flow during pregnancy.

Prenatal Exposure to BPA: The Effects on Hepatic Lipid Metabolism in Male and Female Rat Fetuses.

Bisphenol A (BPA) is an organic chemical compound widely used for manufacturing plastics. BPA exposure originates principally from the diet, but it can also originate from dermal contact. In over 90% of individuals, including pregnant women, BPA is detectable in several body fluids. The effects of this exposure on the fetus are under active investigation in several research laboratories. The aim of our work was to study the impact of prenatal exposure to BPA in the liver of rat fetuses from a sex-dependent point of view. We particularly investigated the effects of prenatal BPA exposure on hepatic lipids because of their crucial role, not only for the liver, but also for the whole-body functions. Our results demonstrate that the liver of rat fetuses, in utero exposed to a very low dose of BPA (2.5 µg/kg/day), displays significant modulations with regard to proteins involved in cholesterol and fatty acid biosynthesis and trafficking. Moreover, an impact on inflammatory process has been observed. All these effects are dependent on sex, being observable only in female rat fetuses. In conclusion, this work demonstrates that maternal exposure to BPA compromises hepatic lipid metabolism in female offspring, and it also reveals the perspective impact of BPA on human health at doses currently considered safe.

Bisphenol a Interferes with Uterine Artery Features and Impairs Rat Feto-Placental Growth.

Bisphenol A (BPA) is a widespread environmental contaminant, found in human fluids and tissues. Maternal BPA exposure is associated with alterations in pregnancy outcomes. Because maternal uterine circulation plays a crucial role in normal placenta and fetal growth, we hypothesized that BPA compromises the function of uterine arteries (UAs) and fetoplacental development. Female rats were orally administered with BPA (2.5, 25 and 250 µg/kg/day) or with its vehicle (ethanol) for 30 days before pregnancy and during the first 20 days of pregnancy. To compare the effect of BPA in the reproductive vs. systemic circulation, it was tested on UAs and mesenteric arteries (MAs). Arteries were isolated and examined by pressure myography. Moreover, fetuses and placentas were weighed to provide an index of reproductive performance. In UAs of BPA-treated rats, lumen diameter, acetylcholine-relaxation and expressions of endothelial nitric oxide synthase 3 (NOS3), estrogen receptor α (ERα) and peroxisome proliferator-activated receptor É£ (PPARÉ£) were reduced. Conversely, no changes were observed in MAs. BPA treatment also reduced placental weights, while fetal weights were increased. For the first time, our results indicate that UAs represent a specific target of BPA during pregnancy and provide insight into the molecular mechanisms that underlie its negative effects on pregnancy outcomes.

Extra Virgin Olive Oil Phenols Vasodilate Rat MesentericResistance Artery via Phospholipase C (PLC)-CalciumMicrodomains-Potassium Channels (BKCa) Signals.

Recent evidence suggests that the reason Extra Virgin Olive Oil (EVOO) lowers blood pressure and reduces the risk of developing hypertension is partly due to minor components of EVOO, such as phenols. However, little is still known about the mechanism(s) through which EVOO phenols mediate anti-hypertensive effects. The aim of the present study was to investigate the mechanisms of action of EVOO phenols on mesenteric resistance arteries. A pressure myograph was used to test the effect of EVOO phenols on isolated mesenteric arteries in the presence of specific inhibitors of: 1) BKca channels (Paxillin, 10-5 M); 2) L-type calcium channels (Verapamil, 10-5 M); 3) Ryanodine receptor, RyR (Ryanodine, 10-5 M); 4) inositol 1,4,5-triphosphate receptor, IP3R, (2-Aminoethyl diphenylborinate, 2-APB, 3 × 10-3 M); 5) phospholipase C, PLC, (U73122, 10-5 M), and 6) GPCR-Gαi signaling, (Pertussis Toxin, 10-5 M). EVOO phenols induced vasodilation of mesenteric arteries in a dose-dependent manner, and this effect was reduced by pre-incubation with Paxillin, Verapamil, Ryanodine, 2-APB, U73122, and Pertussis Toxin. Our data suggest that EVOO phenol-mediated vasodilation requires activation of BKca channels potentially through a local increase of subcellular calcium microdomains, a pivotal mechanism on the base of artery vasodilation. These findings provide novel mechanistic insights for understanding the vasodilatory properties of EVOO phenols on resistance arteries.

Aging-Related Structural and Functional Changes in Cerebral Arteries: Caloric Restriction (CR) Intervention.

Cerebral arteries play a crucial role in the regulation of blood flow to the brain to satisfy the demand of oxygen and glucose for proper function of the organ. Physiological cerebral blood flow (CBF) is maintained within a normal range in response to changes in blood pressure a mechanism named Cerebral Blood Flow Auto Regulation (CBFAR). Structure and function of cerebral arteries have an important impact on CBFAR. Several studies in human and animals have showed significant morphological and functional changes in cerebral vessels of aged brain associated with a reduced CBF which is also impaired in cerebrovascular pathology linked to brain diseases. Interestingly, one new emergent aspect is the lifelong Calorie Restriction (CR) as a potential intervention to prevent age-related cerebral artery changes and preserve the health of aging brain. This review summarizes the recent literature on the effects of aging on cerebral artery structure and function and the potential of CR as opportunities for prevention and treatment.

Antioxidant/Anti-Inflammatory Effects of Caloric Restriction in an Aged and Obese Rat Model: The Role of Adiponectin.

Caloric restriction (CR) represents a powerful intervention for extending healthspan and lifespan in several animal models, from yeast to primates. Additionally, in humans, CR has been found to induce cardiometabolic adaptations associated with improved health. In this study, we evaluated in an aged and obese rat model the effect of long-term (6 months) caloric restriction (-40%) on the oxidative/inflammatory balance in order to investigate the underlining mechanisms. In plasma, we analyzed the oxidative balance by photometric tests and the adiponectin/tumor necrosis factor-α-induced gene/protein 6 (TSG-6) levels by Western blot analysis. In the white adipose tissue, we examined the protein levels of AdipoR1, pAMPK, NFκB, NRF-2, and glutathione S-tranferase P1 by Western blot analysis. Our results clearly showed that caloric restriction significantly improves the plasmatic oxidative/inflammatory balance in parallel with a major increase in circulating adiponectin levels. Additionally, at the level of adipose tissue, we found a positive modulation of both anti-inflammatory and antioxidant pathways. These adaptations, induced by caloric restriction, with the achievement of normal weight, suggest that inflammatory and redox imbalance in obese aged rats appear to be more linked to obesity than to aging.

Extra Virgin Olive Oil Phenols Dilate the Rat Mesenteric Artery by Activation of BKCa2+ Channels in Smooth Muscle Cells.

Accumulating evidence has shown the beneficial health effects of extra virgin olive oil (EVOO) consumption in reducing blood pressure and preventing the risk of developing hypertension. Some studies associate the hypotensive activity of EVOO to a minor component-the phenols. This study was designed to investigate the effects of EVOO phenols on the rat resistance mesenteric artery (MA) and to find out the possible vascular pathways involved. The experiments were carried out using a pressurized myograph, which allowed the effects of phenols on isolated MA to be tested under different conditions: (a) with endothelium removed; (b) with inhibition of nitric oxide synthase by Nω-Nitro-l-arginine methyl ester hydrochloride (l-NAME, 10-4 M) + Nω-Nitro-l-arginine (l-NNA, 10-4 M) ; (c) with inhibition of cyclooxygenase by indomethacin (10-5 M); (d) with inhibition of guanylate cyclase by 1H-[1,2,4]Oxadiazolo[4,3-a]quinoxalin-1-one (ODQ,10-5 M) or adenylate cyclase by 9-(Tetrahydro-2'-furyl)adenine (SQ, 10-5 M); (e) with depolarization by high potassium chloride (40 mM); and (f) with inhibition of the large conductance Ca2+-potassium channels (BKCa2+) with paxilline (10-5 M). EVOO phenols induce vasodilation of the endothelium, mediated by a direct effect on smooth muscle cells (SMC) by activation of BKCa2+ channels, an action by which phenols can regulate the vascular tone of the resistance artery. Phenols can be regarded as bioactive molecules that may contribute to the antihypertensive effects of EVOO.

Maternal Dietary Exposure to Low-Dose Bisphenol A Affects Metabolic and Signaling Pathways in the Brain of Rat Fetuses.

Bisphenol A (BPA) is a synthetic compound widely used for the production of polycarbonate plasticware and epoxy resins. BPA exposure is widespread and more than 90% of individuals have detectable amounts of the molecule in their body fluids, which originates primarily from diet. Here, we investigated whether prenatal exposure to BPA affects the mevalonate (MVA) pathway in rat brain fetuses, and whether potential effects are sex-dependent. The MVA pathway is important for brain development and function. Our results demonstrate that the fetal brain, exposed in utero to a very low dose of BPA (2.5 µg/kg/day), displayed altered MVA pathway activation, increased protein prenylation, and a decreased level of pro-BDNF. Interestingly, the BPA-induced effects on estrogen receptor α were sex-dependent. In conclusion, this work demonstrates intergenerational effects of BPA on the brain at very low doses. Our results reveal new targets for BPA-induced interference and underline the impacts of BPA on health.

Influence of Estrogens on Uterine Vascular Adaptation in Normal and Preeclamptic Pregnancies.

During pregnancy, the maternal cardiovascular system undergoes significant changes, including increased heart rate, cardiac output, plasma volume, and uteroplacental blood flow (UPBF) that are required for a successful pregnancy outcome. The increased UPBF is secondary to profound circumferential growth that extends from the downstream small spiral arteries to the upstream conduit main uterine artery. Although some of the mechanisms underlying uterine vascular remodeling are, in part, known, the factors that drive the remodeling are less clear. That higher circulating levels of estrogens are positively correlated with gestational uterine vascular remodeling suggests their involvement in this process. Estrogens binding to the estrogen receptors expressed in cytotrophoblast cells and in the uterine artery wall stimulate an outward hypertrophic remodeling of uterine vasculature. In preeclampsia, generally lower concentrations of estrogens limit the proper uterine remodeling, thereby reducing UPBF increases and restricting the growth of the fetus. This review aims to report estrogenic regulation of the maternal uterine circulatory adaptation in physiological and pathological pregnancy that favors vasodilation, and to consider the underlying molecular mechanisms by which estrogens regulate uteroplacental hemodynamics.

Altered Endothelial Nitric Oxide Signaling as a Paradigm for Maternal Vascular Maladaptation in Preeclampsia.

PURPOSE OF REVIEW: The goal of this review is to present the newest insights into what we view as a central failure of cardiovascular adaptation in preeclampsia (PE) by focusing on one clinically significant manifestation of maternal endothelial dysfunction: nitric oxide signaling. The etiology, symptoms, and current theories of the PE syndrome are described first, followed by a review of the available evidence, and underlying causes of reduced endothelial nitric oxide (NO) signaling in PE. RECENT FINDINGS: PE maladaptations include, but are not limited to, altered physiological stimulatory inputs (e.g., estrogen; VEGF/PlGF; shear stress) and substrates (L-Arg; ADMA), augmented placental secretion of anti-angiogenic and inflammatory factors such as sFlt-1 and Eng, changes in eNOS (polymorphisms, expression), and reduced bioavailability of NO secondary to oxidative stress. PE is a complex obstetrical syndrome that is associated with maternal vascular dysfunction. Diminished peripheral endothelial vasodilator influence in general, and of NO signaling specifically, are key in driving disease progression and severity.

Pregnancy Augments G Protein Estrogen Receptor (GPER) Induced Vasodilation in Rat Uterine Arteries via the Nitric Oxide - cGMP Signaling Pathway.

BACKGROUND: The regulation of vascular tone in the uterine circulation is a key determinant of appropriate uteroplacental blood perfusion and successful pregnancy outcome. Estrogens, which increase in the maternal circulation throughout pregnancy, can exert acute vasodilatory actions. Recently a third estrogen receptor named GPER (G protein-coupled estrogen receptor) was identified and, although several studies have shown vasodilatory effects in several vascular beds, nothing is known about its role in the uterine vasculature. AIM: The aim of this study was to determine the function of GPER in uterine arteries mainly during pregnancy. Uterine arteries were isolated from nonpregnant and pregnant rats. METHODS: Vessels were contracted with phenylephrine and then incubated with incremental doses (10-12-10-5 M) of the selective GPER agonist G1. RESULTS: G1 induced a dose-dependent vasodilation which was: 1) significantly increased in pregnancy, 2) endothelium-dependent, 3) primarily mediated by NO/cGMP pathway and 4) unaffected by BKca channel inhibition. CONCLUSION: This is the first study to show the potential importance of GPER signaling in reducing uterine vascular tone during pregnancy. GPER may therefore play a previously unrecognized role in the regulation of uteroplacental blood flow and normal fetus growth.

Hyperandrogenism and Insulin Resistance, Not Changes in Body Weight, Mediate the Development of Endothelial Dysfunction in a Female Rat Model of Polycystic Ovary Syndrome (PCOS).

This study was designed to differentiate the contributions of hyperandrogenism, insulin resistance (IR), and body weight to the development of endothelial dysfunction in polycystic ovary syndrome and determine the effectiveness of insulin sensitization and antiandrogenic therapy after the establishment of vascular and metabolic dysfunction using a rat model of polycystic ovary syndrome. We hypothesized that the observed endothelial dysfunction was a direct steroidal effect, as opposed to changes in insulin sensitivity or body weight. Prepubertal female rats were randomized to the implantation of a pellet containing DHT or sham procedure. In phase 1, DHT-exposed animals were randomized to pair feeding to prevent weight gain or metformin, an insulin-sensitizing agent, from 5 to 14 weeks. In phase 2, DHT-exposed animals were randomized to treatment with metformin or flutamide, a nonsteroidal androgen receptor blocker from 12 to 16 weeks. Endothelial function was assessed by the vasodilatory response of preconstricted arteries to acetylcholine. Serum steroid levels were analyzed in phase 1 animals. Fasting blood glucose and plasma insulin were analyzed and homeostasis model assessment index calculated in all animals. Our data confirm the presence of endothelial dysfunction as well as increased body weight, hypertension, hyperinsulinemia, and greater IR among DHT-treated animals. Even when normal weight was maintained through pair feeding, endothelial dysfunction, hyperinsulinemia, and IR still developed. Furthermore, despite weight gain, treatment with metformin and flutamide improved insulin sensitivity and blood pressure and restored normal endothelial function. Therefore, the observed endothelial dysfunction is most likely a direct result of hyperandrogenism-induced reductions in insulin sensitivity, as opposed to weight gain.

Uterine distension differentially affects remodelling and distensibility of the uterine vasculature in non-pregnant rats.

During pregnancy the mammalian uterine circulation undergoes significant expansive remodelling necessary for normal pregnancy outcome. The underlying mechanisms are poorly defined. The goal of this study was to test the hypothesis that myometrial stretch actively stimulates uterine vascular remodelling by developing a new surgical approach to induce unilateral uterine distension in non-pregnant rats. Three weeks after surgery, which consisted of an infusion of medical-grade silicone into the uterine lumen, main and mesometrial uterine artery and vein length, diameter and distensibility were recorded. Radial artery diameter, distensibility and vascular smooth muscle mitotic rate (Ki67 staining) were also measured. Unilateral uterine distension resulted in significant increases in the length of main uterine artery and vein and mesometrial segments but had no effect on vessel diameter or distensibility. In contrast, there were significant increases in the diameter of the radial arteries associated with the distended uterus. These changes were accompanied by reduced arterial distensibility and increased vascular muscle hyperplasia. In summary, this is the first report to show that myometrial stretch is a sufficient stimulus to induce significant remodelling of uterine vessels in non-pregnant rats. Moreover, the results indicate differential regulation of these growth processes as a function of vessel size and type.

Effects of etonogestrel treatment in the reproductive organs and uterine arteries of nonoophorectomized guinea pigs.

The endometria of women treated with long-term progestin-only contraceptives (LTPOCs) display abnormally enlarged, fragile blood vessels, decreased endometrial blood flow, oxidative stress, and unpredictable focal abnormal endometrial bleeding. Because human studies on the effects of LTPOC treatment are constrained for ethical and practical reasons, we assessed the suitability of nonoophorectomized guinea pigs (GPs) to best mimic the hormonal milieu of women. The present study demonstrates that treatment of GPs parallels the morphological changes following LTPOC treatment of the human endometrium and ovaries. Specifically, treatment resulted in larger hyperemic, uteri compared with controls. Histopathologic and immunohistochemical analysis demonstrated fewer endometrial glands, decreased luminal mucus, increased numbers of blood vessels, and focal hemorrhage. While increased staining for the cell mitosis marker, Ki67, was present in the zona functionalis, no such increase occurred in the basalis. Lastly, effects on vasomotor features of uterine arteries suggest changes that favor increased resistance and reduced blood flow promoting decreased ability to withstand elevations in transmural pressure.

Endothelial-derived hyperpolarization factor (EDHF) contributes to PlGF-induced dilation of mesenteric resistance arteries from pregnant rats.

The aim of this study was to investigate the cellular mechanism involved in the potent vasodilatory action of PlGF on mesenteric resistance arteries from pregnant rats. PlGF (3 nM) induced a vasodilation of 64 ± 3.8% that was completely abolished by endothelial denudation. Significant dilation (28 ± 4.0%) remained, however, in the presence of nitric oxide synthase and cyclooxygenase inhibition, and was associated with significant reductions in vascular smooth muscle cell calcium. Absence of dilation in potassium-depolarizing solution (30 mM) confirmed its dependence on endothelial-derived hyperpolarization factor. Subsequent studies established that vasodilation was abolished by pharmacologic inhibition of SK(Ca) (apamin) and BK(Ca) (iberiotoxin) but not IK(Ca) (tram-34) potassium channels. In summary, PlGF acts through the release of a combination of endothelium-derived relaxation factors. Based on the results of potassium channel blockade, we suggest that it induces endothelial hyperpolarization via SK(Ca) channel activation; this, in turn, leads to the release of a diffusible mediator that activates vascular smooth muscle BK(Ca) channels, hyperpolarization and vasodilation. This is the first study to identify the mechanism for PlGF/VEGFR-1 resistance artery dilation in the pregnant state, whose attenuation likely contributes to the systemic hypertension characteristic of pre- eclampsia.

Hemodynamic, vascular, and reproductive impact of FMS-like tyrosine kinase 1 (FLT1) blockade on the uteroplacental circulation during normal mouse pregnancy.

To investigate the role of FMS-like tyrosine kinase 1 (FLT1, also known as VEGFR1) signaling during pregnancy, mice were injected with anti-FLT1 neutralizing antibody (Ab) beginning on Gestational Day 8 or 12 and every other day thereafter until Day 18; vehicle-only injected mice served as controls. Uterine artery blood flow was measured with ultrasound on Days 13 and 18, and morphometric measurements of the uterine arcade were carried out on Day 19 to provide a measure of gestational vascular remodeling; reproductive performance was evaluated by determining litter size, resorption rates, and pup and placental weights. Ab injections beginning on Day 8 or Day 12 resulted in significant reductions of uterine artery peak systolic and diastolic flows at Days 13 and 18. In addition, normal reproductive function was compromised, as evidenced by a significant reduction in average number of viable pups along with enhanced resorption rates. Reproductive performance was also significantly compromised in this group, although less severely. There was no evidence of a reduction in main uterine artery diameters, though arterial distensibility was reduced, and the diameter of the main uterine vein was significantly smaller in the Ab-injected mice. Significant reductions in main uterine artery and segmental artery length were also noted. Placental and pup weights were similar in all the groups. FLT1 inhibition during murine pregnancy impaired blood flow to the fetal-placental unit, compromised several indices of vascular remodeling, reduced fecundity, and increased fetal reabsorptions. The effects of FLT1 inhibition are most pronounced when targeted during early pregnancy.

Endothelial dysfunction in a rat model of PCOS: evidence of increased vasoconstrictor prostanoid activity.

Clinical research demonstrates an association between polycystic ovary syndrome (PCOS) and endothelial dysfunction, a pathological state widely believed to be a hallmark of vascular disease; the underlying pathways, however, have not been defined. The purpose of this study was to characterize endothelial function in resistance arteries in a novel rat model of PCOS. Female rats were randomized at 3-4 wk to implantation of a 7.5-mg, 90-d dihydrotestosterone (DHT) pellet or a matched placebo. At 15-16 wk, experiments were performed on isolated mesenteric resistance arteries using a pressurized arteriograph. Endothelial function was assessed by the vasodilatory response of preconstricted arteries to acetylcholine (ACh) in the absence and presence of inhibitors for cyclooxygenase (indomethacin) and the thromboxane prostanoid receptor antagonist (SQ29,548). Distensibility was evaluated by measuring vessel diameter from 3-100 mm Hg, and elastin/collagen content was calculated on formalin-fixed vessels. Serum steroid levels were analyzed by sensitive RIA. DHT-induced PCOS rats were heavier, cycled irregularly, and had elevated blood pressure and smaller arterial lumens than controls. Furthermore, DHT vessels showed significantly reduced vasodilatory efficacy to ACh (with no change in sensitivity), reduced distensibility, and increased elastin content compared with controls. Within DHT animals, maximal dilation correlated negatively to DHT levels (r = -0.72) but not to body weight. Preincubation with either indomethacin or SC29,548 abrogated the dysfunction and restored full efficacy to ACh (P < 0.05). This is the first report to demonstrate the presence of endothelial dysfunction in a hyperandrogenic rat model of PCOS and to identify the role of vasoconstrictor prostanoids, allowing for more targeted research regarding the development of disease and potential therapeutic interventions.

The chromogranin A peptide vasostatin-I inhibits gap formation and signal transduction mediated by inflammatory agents in cultured bovine pulmonary and coronary arterial endothelial cells.

The proinflammatory agent tumour necrosis factor alpha (TNFalpha) is one of several agents causing vascular leakage. The N-terminal domain of CgA, vasostatin-I (CgA1-76), has recently been reported to inhibit TNFalpha induced gap formation in human umbilical venous endothelial cells. Here we report on the effect of recombinant human CgA1-78, vasostatin-I, on TNFalpha induced gap formation in two model systems of vascular leakage in arterial endothelial cells of bovine pulmonary (BPAEC) and coronary (BCAEC) origin. Vasostatin-I inhibited the TNFalpha induced gap formation in both models, being inactive in the unstimulated cells. The phosphorylation of p38MAP kinase in TNFalpha activated BPAEC was markedly attenuated in the presence of vasostatin-I and the inhibitory effect corresponded to that of the specific p38MAPK inhibitor SB203580. Vasostatin-I also inhibited the phosphorylation of p38MAPK induced by both thrombin and pertussis toxin in these cells. The results demonstrate that vasostatin-I has inhibitory effects on TNFalpha-induced disruption of confluent layers of cultured pulmonary and coronary arterial endothelial cells. This suggests that vasostatin-I may affect endothelial barrier dysfunction also in arterial vascular beds. Furthermore, the inhibitory activity of vasostatin-I may be associated with the p38MAPK signalling cascade via a pertussis toxin sensitive, presumably Galphai coupled mechanism.