BACKGROUND: ovulation is associated with degradation of the follicular apex vasodilatation and increased permeability of ovarian vessels. These changes may maintain or increase intrafollicular pressure (IFP) at ovulation to cause rupture of the follicular wall. OBJECTIVE: to investigate the possible regulation of IFP during the ovulatory process. STUDY DESIGN: immature ...

Nitroxyl anion (NO(-)) is the one-electron reduction product of nitric oxide (NO( small middle dot)) and is enzymatically generated by NO synthase in vitro. The physiologic activity and mechanism of action of NO(-) in vivo remains unknown. The NO(-) generator Angeli's salt (AS, Na(2)N(2)O(3)) was administered to conscious chronically instrumented ...

OBJECTIVE: Recent evidence suggests a possible role for nitric oxide (NO) in atrial natriuretic peptide-induced blood pressure effects. We tested the hypothesis that C-type natriuretic peptide (CNP)-mediated relaxation of the rat coronary circulation involves NO and activation of soluble guanylyl cyclase. METHODS: Rat hearts (n=6 per group) were perfused in ...

BACKGROUND: Long-term inhibition of nitric oxide synthase (NOS) is known to induce hypertension and perivascular fibrosis. Recent evidence also suggests that long-term NOS inhibition induces expression of plasminogen activator inhibitor-1 (PAI-1) in vascular tissues and that PAI-1 may contribute to the development of fibrosis after chemical or ionizing injury. On ...

BACKGROUND: This study was performed to determine whether a combined therapy of nitric oxide (NO) inhalation and nitric oxide synthase (NOS) inhibitor is effective in experimental animals with endotoxin-induced refractive hypotension accompanied by pulmonary hypertension. METHODS: Escherichia coli lipopolysaccharide (1 mg/kg) was administered to 10 newborn piglets to induce endotoxemia. ...

It was hypothesized that hypoxia may inhibit nitric oxide (NO) production by reducing the availability of endothelial NO synthase (NOS III) substrate. To evaluate the effect of L-arginine on the NO release in high altitude, 11 subjects were infused with L-arginine (0.5 g x kg(-1)) during 30 min in normoxia ...

OBJECTIVES: Essential hypertension is associated with impaired endothelium-dependent vasodilation caused by oxygen free radical-induced nitric oxide (NO) breakdown. Since calcium antagonists can improve endothelial function in hypertensive patients, we tested whether this beneficial effect could be related to restoration of NO availability by antioxidant activity. METHODS: In 10 healthy subjects ...

BACKGROUND: Vascular endothelial dysfunction may predict future atherosclerosis. Hence, an antihypertensive agent that reverses endothelial dysfunction and lowers blood pressure might improve the prognosis of patients with hypertension. We hypothesized that nebivolol, a vasodilating beta-blocker, could improve endothelial dysfunction. We tested this hypothesis by comparing the effects of nebivolol and ...

1. We studied the effect of adrenomedullin (ADM) on fluid efflux from the splenic vasculature into extravascular spaces. 2. Splenic arterial infusion of ADM (1, 3 and 9 ng min(-1); n = 9, 11 and 10, respectively) caused a dose-dependent increase in intrasplenic fluid efflux (+0.6 +/- 0.3 (saline) vs. ...

Despite intensive investigation, the role of nitric oxide (NO) in cholinergic modulation of myocardial contractility remains unresolved. The left anterior descending coronary artery of 34 anesthetized, open-chest dogs was perfused via an extracorporeal circuit. Segmental shortening (SS) was measured with ultrasonic crystals and coronary blood flow (CBF) was measured with ...

Controlled release of nitric oxide (NO*) may be useful in the treatment of a variety of vascular disorders. NO* donors of the diazeniumdiolate family with different rates of spontaneous NO* release have been synthesized. In the current study responses to seven diazeniumdiolate NO* donors (DEA/NO*, DETA/NO*, OXI/NO*, PIPERAZI/NO*, PROLI/NO*, SPER/NO*, ...

Diesel exhaust particles cause an impairment of endothelium-dependent vasorelaxation and are associated with cardiopulmonary-related diseases and mortality, but the mechanistic details are poorly understood. Since we reported previously that phenanthraquinone, an environmental chemical contained in diesel exhaust particles, suppresses neuronal nitric oxide synthase (nNOS) activity by shunting electrons away from ...

BACKGROUND: The effects of pulsatile flow on endothelium-derived nitric oxide-mediated vasodilation are not fully elucidated in an in vivo model. METHODS: A left ventricular assist device was established in 10 anesthetized dogs with a centrifugal pump and an air-driven pneumatic pump. The systemic circulation was subjected to step changes in ...

OBJECTIVES: The purpose of this study is to assess the role of the nitric oxide (NO) pathway in protamine-induced cardiotoxicity and to formulate a possible explanation for this adverse effect. METHODS: Isolated rat hearts were perfused by Krebs--Henseleit (KH) solution using a modified Langendorff model. They were randomized into three ...

A 14 month old child presented for investigation of tachypnoea. No parenchymal lung disease was shown on chest x ray. On echocardiography there was normal intracardiac anatomy with significant pulmonary hypertension. At cardiac catheterisation the presence of primary pulmonary hypertension was confirmed, with a partial response to inhaled nitric oxide ...

On withdrawal of inhalation of nitric oxide (INO) administered after lung injury, pulmonary artery pressure (PAP) and arterial oxygen tension (Pa(O(2))) may deteriorate more than before INO (rebound response). In this study, we investigated the possible roles of endothelin (ET)-1 and nitric oxide (NO) synthase (NOS) activity in the short ...

BACKGROUND: The enzyme 11beta-hydroxysteroid dehydrogenase (11beta-HSD) prevents inappropriate activation of the nonselective mineralocorticoid receptors by glucocorticoids. Renal activity of 11beta-HSD is decreased in patients with apparent mineralocorticoid excess (SAME), licorice-induced hypertension, and essential hypertension. Although expressed in vascular cells, the role of 11beta-HSD in the regulation of vascular tone remains ...

Apelin is an endogenous ligand of the human orphan receptor APJ. We detected apelin-like immunoreactivity in the adipocytes, gastric mucosa, and Kupffer cells in the liver. We also detected apelin-like immunoreactivity localized within the endothelia of small arteries in various organs. Further, it was found that mean arterial pressure after ...

OBJECTIVE: To test the hypothesis that nitric oxide inhalation facilitates CO2 elimination by decreasing alveolar deadspace in an ovine model of acute lung injury. DESIGN: Prospective, placebo-controlled, randomized, crossover model. SETTING: University research laboratory. SUBJECTS: Eleven mixed-breed adult sheep. INTERVENTIONS: To induce acute lung injury, hydrochloric acid was instilled into ...

We investigated the contribution of neuronal or inducible nitric oxide synthase (nNOS or iNOS) at the rostral ventrolateral medulla (RVLM) to central cardiovascular regulation by endogenous nitric oxide (NO), using Sprague-Dawley rats anaesthetized and maintained with propofol. Microinjection bilaterally into the RVLM of a NO trapping agent, carboxy-2-phenyl-4,4,5,5-tetramethylimidazoline-l-oxy-l-3-oxide (10, 50 ...

Experiments were carried out in conscious chronically instrumented lambs aged 1 (n = 6) and 6 wk (n = 5) to evaluate the arterial baroreflex control of heart rate (HR) during postnatal maturation and to investigate any modulatory role of endogenously produced nitric oxide (NO). Before and after intravenous administration ...

OBJECTIVE: The dihydropyridine calcium antagonist isradipine has anti-atherosclerotic effects in animals and improves endothelium-mediated nitric oxide (NO)-dependent vasodilation in vitro. As improved endothelial function may be beneficial we investigated its effects in patients with a high likelihood of endothelial dysfunction. DESIGN: Thirty patients (two female, age 55.4 +/- 10.5 years) ...

1. Hypoadrenocorticism frequently results in critical hypotension, hypovolaemia, hyponatraemia and hyperkalaemia. Perhaps even more important, hypoadrenocorticoid humans experience decreased vasoconstriction in response to exogenous administration of vasoconstrictors, such as noradrenaline. 2. We studied chronically adrenalectomized adult sheep to test the hypothesis that the reduction in pressor responsiveness is the result ...

Sildenafil is a selective phosphodiesterase type 5 inhibitor used in the treatment of erectile dysfunction. We report the use of sildenafil to blunt the rebound pulmonary hypertension seen following withdrawal of inhaled nitric oxide (NO) and milrinone. The relatively long duration of sildenafil's action on pulmonary artery pressures and lack ...

Nothing is known about the effects of nitric oxide (NO) on cardiac performance in fish. Using an in vitro working heart preparation that generates physiological values of output pressure, cardiac output and ventricular work and power, we assessed the effects of NO on the cardiac performance of the eel Anguilla ...

Asymmetrical dimethyl-L-arginine (ADMA) is an endogenous inhibitor of nitric oxide synthase. We hypothesized that plasma levels of ADMA could be increased in patients with congenital heart disease and pulmonary hypertension. Cardiac catheterization was performed in 20 children and young adults with congenital heart disease with a median age of 10 ...

Traditionally, nitric oxide-mediated alteration in blood vessel tone has been inferred from changes in flow in response to physical and pharmacological interventions using plethysmographic or ultrasonic techniques. We hypothesized that alteration in pulsatile arterial function may represent a more sensitive measure to detect and monitor nitric oxide-mediated modulation of arterial ...

The aim of this study was to elucidate cardiac and regional hemodynamics using a nonspecific inhibitor of the constitutive and inducible nitric oxide synthase (NOS), N-methyl-L-arginine (L-NMA), and a specific inhibitor of the inducible NOS, aminoguanidine, in conscious pigs. Animals were divided into two groups. After hemodynamics were stabilized, animals ...

FK409 decomposes and releases nitric oxide (NO) spontaneously when it is dissolved in phosphate buffer solution at 37 degrees C. With the use of this NO donor, the effect of exogenous NO on cardiac contractility was examined by assessing Emax. alpha-chloralose-anaesthetized dogs were instrumented for measurements of left ventricular (LV) ...

Endothelium takes part in the regulation of vascular tone through the production of endothelium-derived relaxing factor, nitric oxide (NO), and the contracting factor endothelin-(ET-1). Induction of ET-1 and NO is influenced by many stimuli including hypoxia and shear stress. Some of these stimuli may arise during coronary angiography (CAG). In ...

We hypothesized that nitric oxide (NO) contributes to intrasplenic fluid extravasation by inducing greater relaxation in splenic resistance arteries than veins such that intrasplenic microvascular pressure (P(C)) rises. Fluid efflux was estimated by measuring the difference between splenic blood inflow and outflow. Intrasplenic infusion of the NO donor S-nitroso-N-acetylpenicillamine (SNAP) ...

PURPOSE: Zaprinast, dipyridamole and sildenafil were injected into the corpora cavernosa of cats to determine whether changes in the steady state level of cyclic guanosine monophosphate (cGMP) induced by inhibiting type 5 phosphodiesterase would cause an erectile response. MATERIALS AND METHODS: Increases in intracavernous pressure, penile length and erectile response ...

The purpose of this study was to determine whether nitric oxide (NO) contributes to the hypotensive state induced by prolonged environmental heat (EH) stress. Ketamine-anesthetized rats were instrumented for the measurement of arterial blood pressure, electrocardiogram, and temperature at four sites. Rats were exposed to EH (ambient temperature, 40 +/- ...

Nitric oxide plays a key role as a vasodilating agent and its deficiency is associated with ischemic heart diseases. The aim of this study was to induce biochemical alterations associated with ischemic heart lesions by blocking nitric oxide synthase. L-NAME, a nitric oxide synthase inhibitor, was administered to rabbits and ...

The objective of this study was to examine the effects of gender and age on electrical field stimulation (EFS)-induced vasoconstriction. Fisher 344 rats were studied: young females (YF, n = 38), young males (YM, n = 29), old females (OF, n = 33), and old males (OM, n = 30). ...

Functional and morphological changes of blood vessels in cyclosporine A (CsA)-induced hypertension and nephrotoxicity were studied in spontaneously hypertensive rats (SHR). The role of the L-arginine-nitric oxide (NO) pathway and the importance of oxidative stress in CsA toxicity were also assessed. SHR (7-8 week old) on a high-sodium diet were ...

The early cardiovascular effects resulting from an acute spinal cord injury (SCI) produced by a contusion procedure at T5-T6 were evaluated in anaesthetized rats. The mean arterial pressure (MAP) and heart rate (HR) were measured during one hour after the injury. A marked decrease in MAP and HR was observed ...

Hypertension contributes to cardiac and cerebrovascular complications in HD patients. Endogenous inhibitors of nitric oxide synthase accumulate in renal failure and may interfere with the regulation of vascular tone. We investigated the elimination of asymmetric dimethylarginine (ADMA) by using biocompatible Polyamide Strade mark membranes in low-flux (Polyflux 6L) or high-flux ...

OBJECTIVE: We tested the hypothesis that carbon monoxide might participate in the modulation of hypoxic pulmonary vasoconstriction (HPV) by prostacyclin (PGI2) and nitric oxide. DESIGN: Prospective, interventional study. SETTING: University laboratory. SUBJECTS: Nineteen intact anesthetized mongrel dogs. INTERVENTIONS: Right heart catheterization for the measurements of mean pulmonary artery pressure (Ppa), ...

In the middle cerebral artery (MCA), the presence of nitric oxide (NO) is responsible for maintaining a more dilated state than in its absence during increases in extracellular K(+) and osmolality. The purpose of the present study was to determine whether the involvement of NO was due to (a) a ...

STUDY DESIGN: This in vitro study clarifies the role of nitric oxide (NO) in human lumbar intervertebral disc metabolism. OBJECTIVE: To investigate the effects of NO on proteoglycan synthesis in human lumbar discs and to test the hypothesis that NO is a mediator of the changes in proteoglycan synthesis in ...

To investigate the oxygenation and haemodynamic dose response to inhaled nitric oxide in neonates with persistent pulmonary hypertension (PPHN), we gave seven neonates nitric oxide and measured directly pulmonary arterial pressure. Inhaled nitric oxide produced peak improvement in oxygenation at 5 parts per million (ppm) whereas peak improvement in the ...

The hypertensive rat model was made by chronic stress of electric foot-shocks and noises. On such hypertensive rats, when anesthetized with urethane and chloralose, the electroacupuncture (EA) to bilateral "Zusanli (st.36)" acupoints for 20 min, could result in a depressor (including both systolic and diastolic pressure) and bradycardiac response as ...

Endothelial nitric oxide synthase (eNOS) serves a number of functions in the vasculature. In response to stimuli such as shear stress or acetylcholine, eNOS catalyses the production of nitric oxide (NO) from L-arginine. The NO diffuses across the endothelium into neighbouring smooth muscle and induces vasodilation. NO also acts locally ...

Vegetarians are known to have a low incidence of cardiovascular diseases and lower blood pressure compared to non-vegetarians. The exact cause for this is not known. In the present study, it was found that, in general, vegetarians (female > males) have a higher concentrations of anti-oxidant enzymes: catalase and superoxide ...

This study evaluated the effects of progressive nitric oxide (NO) inhibition in the regulation of systemic and regional hemodynamics and renal function in anesthetized dogs. The N(G)-nitro-L-arginine methyl ester group (n = 9) received progressive doses of 0.1, 1, 10, and 50 microg. kg(-1). min(-1). Renal (RBF), mesenteric (MBF), iliac ...

We recently demonstrated that a pressure-induced vasodilation results from local nonnociceptive stimulation of the skin of the human hand. We aimed to test the hypothesis that this vasodilation was not a short-lived response to a single type of pressure strain, but could be a widely activated and prolonged protective cutaneous ...

Yawing was induced by microinjections of L-glutamate, cyanide and a nitric oxide-releasing compound (NOC12) into the paraventricular nucleus of the hypothalamus (PVN) in anesthetized, spontaneously breathing rats. To evaluate physiological aspects of yawning, we monitored intercostal electromyogram (EMG) as an index of inspiratory activity, digastric EMG, blood pressure and electrocorticogram ...

Based on the previous finding that locally produced nitric oxide (NO) and endothelin (ET) exert competing effects on choroidal resistance vessels, the present study sought to further characterize the pharmacology of ET in the choroid. The specific goal was to quantify the choroidal blood flow responses to acute changes in ...

OBJECTIVES: We sought to compare the responses of patients with pulmonary hypertension from primary and secondary causes (PPH and SPH, respectively) to inhaled nitric oxide (iNO) in the cardiac catheterization laboratory. BACKGROUND: Pulmonary hypertension can lead to right ventricular pressure overload and failure. Although vasodilators are effective as therapy in ...