The effects of helodermin, a basic 35-amino acid peptide isolated from the venom of a lizard salivary gland, on arterial blood pressure and heart rate were examined in the rat, focusing on the possibility that activation of ATP sensitive K+ (K(ATP)) channels is involved in the responses. The results were ...

Estrogen deficiency, hyperinsulinemia, type II diabetes, atherosclerosis, and a past history of elevated blood pressure may be associated with increased risk of Alzheimer's disease (AD). Common to all of these risk factors is a diminished capacity of vascular endothelium to generate nitric oxide (NO). Vascular NO has the potential to ...

The effects of [Leu13]motilin were examined in vivo after its intravenous administration into anesthetized dogs and in vitro with isolated preparations of canine mesenteric artery. [Leu13]Motilin (0.1-10 nmol x kg(-1), i.v.) induced both strong and clustered phasic contractions in the gastric antrum and duodenum. At doses of over 1 nmol ...

BACKGROUND: The response to inhaled nitric oxide and prone positioning was investigated in 47 patients with adult respiratory distress syndrome to test the hypothesis that inhalation of nitric oxide when in the prone position would result in additive improvement in oxygenation. METHODS: The authors prospectively studied patients of both genders ...

The underlying mechanisms of hemoglobin (Hb)-induced vasoconstriction are not yet well understood. The aim of this study was to elucidate the influence of nitric oxide (NO) and endothelin (ET) on Hb-induced pulmonary vasoconstriction. Therefore, an autologous Hb preparation was administered into isolated rabbit lungs, in which pulmonary artery pressure (PAP) ...

Hypovolemia has been associated with the induction of nitric oxide synthase which is believed to result in an over-production of nitric oxide. In the present study, we have examined the effects of noradrenaline following haemorrhage on cardiac output, blood pressure, mean circulatory filling pressure and vascular resistance in anaesthetized rats ...

It is thought that elevated levels of reactive oxygen metabolites contribute to the dysfunction of vascular endothelium in hypertension. We hypothesized that high intravascular pressure itself elicits production of superoxide, which then interferes with nitric oxide (NO)-mediated responses of arterioles. Thus, isolated arterioles (approximately 80 microm in diameter) from gracilis ...

BACKGROUND: Ischemia/reperfusion injury to transplanted organs may be associated with loss of endothelial release of nitric oxide. The aim of this study was to determine whether supplementation of an extracellular-based cardioplegic solution in routine clinical use at our institution with nitric oxide (as diethylamine NONOate) enhanced poststorage functionality of an ...

OBJECTIVE: Nitric oxide is a vasodilating and blood pressure lowering substance. To investigate whether calcium antagonists or angiotensin-converting enzyme (ACE) inhibitors increase vascular nitric oxide activity, we assessed systemic and renal vascular sensitivity to nitric oxide synthase inhibition in hypertensives on and off medication. METHODS: Ten essential hypertensive patients, aged ...

Adaptation of the cerebral circulation to microgravity was investigated in rat middle cerebral arteries after 20 days of hindlimb unweighting (HU). Myogenic responses were measured in isolated, pressurized arteries from HU and control animals. Maximal passive lumen diameters, obtained in the absence of extracellular Ca2+ plus EDTA, were not significantly ...

The aim of this study was to investigate whether nitric oxide might be involved in the adaptation of the cardiovascular system in sodium and water loaded organisms. The effects of a semi-chronic (4 day) inhibition of nitric oxide production were studied in normovolemic and per os sodium and water loaded ...

We previously showed [Am. J. Physiol. 272 (Heart Circ. Physiol. 41): H2337-H2342, 1997] that nicotine impairs endothelium-dependent arteriolar dilatation. However, mechanisms that accounted for the effect of nicotine on endothelium-dependent vasodilatation were not examined. Thus the goal of this study was to examine the role of oxygen radicals in nicotine-induced ...

Vascular endothelium releases nitric oxide (NO), an important vasodilator that is continuously synthesised by the constitutive enzyme, endothelial nitric oxide synthase (NOS). This maintains a constant vasodilator tone which is diminished in adult hypertension, due to reduced endothelium-dependent vascular relaxation, which is NO dependent. In childhood, however, hypertension is often ...

The interaction between constitutive nitric oxide and oxygen may depend on the degree of tissue oxygenation and may play a critical role in the pathophysiological response to endotoxaemia. We investigated if hyperoxia (100% O2) attenuated the systemic and pulmonary vasoconstriction and increased biosynthesis of thromboxane B2 (TXB2) and 6-keto-prostaglandin (PG) ...

Patients with clinically stable asthma may show ventilation-perfusion (V'A/Q') mismatch. Nitric oxide (NO), a potent endogenous vasodilator, is increased in exhaled air of asthmatics. Such an increased NO production may be detrimental for optimal V'A/Q' balance owing to the potential inhibition of hypoxic pulmonary vasoconstriction. This study was undertaken to ...

The enzyme heme oxygenase, which exists in inducible (HO-1) and constitutive (HO-2) isoforms, catalyzes the degradation of heme to biliverdin and CO in mammalian tissues. CO has been implicated in the control of vascular tone in a manner similar to that for NO. In the present study, we investigated the ...

Whether nitric oxide (NO) is involved in cutaneous active vasodilation during hyperthermia in humans is unclear. We tested for a role of NO in this process during heat stress (water-perfused suits) in seven healthy subjects. Two forearm sites were instrumented with intradermal microdialysis probes. One site was perfused with the ...

Evidence from investigations of brain microcirculation (pial arterioles) reveals at least 3 different endothelium (EC) dependent mechanisms for dilation. Only one of the three can be triggered by acetylcholine (ACh) and in this vascular bed it is only this path that is dependent upon endothelial nitric oxide synthase (NOS) which ...

Increasing evidence implicates reactive oxygen species in the pathogenesis of hypertension and its cardiovascular complications. By altering the balance in the endothelium between vasoconstrictors such as thromboxane and isoprostanes and vasodilators such as nitric oxide, reactive oxygen species contribute to endothelium-dependent contractions and increased vascular resistance. Antioxidants can restore endothelial ...

OBJECT: The authors tested the hypothesis in a porcine model that inhibition of nitric oxide synthesis during reduced cerebral perfusion pressure (CPP) affected the relative cerebral blood flow (CBF) and the cerebrovascular resistance. METHODS: The CPP was reduced by inducing high cerebrospinal fluid pressure and hemorrhagic hypotension. With continuous blood ...

In this study, the auditory bulla of the gerbil was pressurized, leading to active modeling of the bone of the bulla wall with a significant increase in osteoclast surface and mineral apposition rate. Systemic infusion of L-N(G)-nitro-arginine-methyl ester (L-NAME), an inhibitor of nitric oxide synthase (NOS), inhibited this modeling process. ...

STUDY OBJECTIVE: Elevated pulmonary vascular resistance is a risk factor in heart transplantation and reversibility of high pulmonary vascular resistance is evaluated preoperatively in potential recipients using i.v. vasodilators or inhaled nitric oxide. Prostacyclin is a potent vasodilator, which when inhaled, has selective pulmonary vasodilatory properties. The aim of this ...

1. Nitric oxide is a potent vasodilator which plays a major role in the control of blood pressure. The hyperdynamic circulation of cirrhosis has been linked to nitric oxide.2. We measured neutrophil nitric oxide synthase activity in relation to the level of hepatic dysfunction in patients with liver disease of ...

OBJECTIVE: To test the effect of a continuous infusion of the nitric oxide synthase inhibitor N(G)-monomethyl-L-arginine (L-NMMA) on survival rate and hemodynamics in a pig model of endogenous peritoneal live bacterial sepsis. DESIGN: Prospective, randomized trial. SETTING: Laboratory at a university medical center. SUBJECTS: Thirty-five pigs with an average weight ...

The aim of this study was to examine whether nitric oxide (NO) has an important role in maintaining basal vascular tone in normal man by examining the effects of nitric oxide inhibition using N(G)-monomethyl-L-arginine (L-NMMA) on systemic and pulmonary haemodynamics. Ten normal male volunteers 26 +/- 1.6 years were studied ...

The pulmonary vasorelaxant properties of two NONOates (diazeniumdiolates) were examined because this novel group of nitric oxide (NO) donors may be useful in pulmonary hypertension. MAHMA NONOate ((Z)-1-¿N-Methyl-N-[6-(N-methylammoniohexyl)amino]¿ diazen-1-ium-1,2-diolate) and spermine NONOate ((Z)- 1-¿N-[3-aminopropyl]-N-[4-(3-aminopropylammonio)butyl]-amino¿di azen-1-ium-1,2-diolate) decomposed at different rates (half-lives 1.3 min and 73 min, respectively; 37 degrees C, pH ...

Nitric oxide (NO) is receiving interest because of its use in patients with acute respiratory distress syndrome. Because more studies are being conducted, researchers are discovering a vast array of physiological effects attributable to NO. NO has been implicated as having a role in the endogenous regulation of blood pressure; ...

Peroxynitrite, formed endogenously by the near diffusion-limited reaction of nitric oxide with superoxide anion, induces vascular relaxation. This effect is subject to rapid tachyphylaxis, suggesting that peroxynitrite may alter subsequent vasorelaxant responses. The present study examined the effects of peroxynitrite on mean arterial pressure and hindquarter, renal, and mesenteric vascular ...

To analyze newborn cerebrovascular autoregulation, middle cerebral arteries from 3-4-d-old piglets were cannulated, and diameter changes after transmural pressure variation were measured. After an equilibration period at 30 mm Hg, pressure was modified from 10 to 70 mm Hg in 20-mm Hg steps. Segments with endothelium showed vasodilation during pressure ...

We have determined the role of nitric oxide (NO) in the nucleus of the solitary tract (NTS) of normotensive Wistar rats. The unilateral microinjection of Nomega-nitro-l-arginine methyl ester (10 nmol) to block the synthesis of NO into the NTS significantly decreased the arterial pressure, heart rate (HR) and renal sympathetic ...

Nitric oxide (NO) affects myocardial contractility and myocardial oxygen consumption (MVO2) in vitro. In alpha-chloralose-anesthetized dogs instrumented for the measurements of left ventricular (LV) pressure, LV volume using a conductance catheter, coronary blood flow, and coronary venous oxygen saturation (ScvO2) using a fiber-optic catheter, LV end-systolic pressure-volume relationships (ESPVR) and ...

Systemic administration of adrenergic agonists and nitric oxide donors is used extensively to determine cardiovascular receptor sensitivity. Conclusions regarding receptor sensitivity in the presence of the baroreflex may be misleading. In 8 normal volunteers, we determined the heart rate and blood pressure changes after incremental bolus doses of isoproterenol, phenylephrine, ...

PURPOSE: The effects of sildenafil, a highly selective inhibitor of cyclic guanosine monophosphate-specific phosphodiesterase type 5, on erectile function in the anesthetized dog were evaluated. MATERIALS AND METHODS: In pentobarbital-anesthetized dogs, increases in intracavernosal pressure in the corpus cavernosum and penile blood flow were induced by pelvic nerve stimulation over ...

Small volume intravenous infusions of hypertonic saline (HTS) increase blood pressure, heart rate, adrenocorticotropic hormone (ACTH), and cortisol by mechanisms that are not fully understood. We hypothesized that HTS infusions increase prostaglandin biosynthesis and that a prostaglandin synthase metabolite is responsible for mediating actions of HTS. We further hypothesized that ...

In pressurised resistance arteries in vitro, rapid pressure increases cause a transient "peak" dilatation, followed by a myogenic constriction. The mechanism of transient dilatation was investigated in isolated rat cerebral arteries in vitro using pressure myography. The peak increased with the amplitude of the pressure step. A near-maximal dilatation to ...

Endothelial function has been shown to be impaired in patients with essential hypertension. The purpose of the present study was to determine whether antihypertensive drug therapy improves impaired endothelium-dependent renal vasorelaxation in essential hypertensive patients without atherosclerosis. We evaluated the effects of intravenous infusion of L-arginine (500 mg/kg given over ...

OBJECTIVE: To look for the effects of inhaled nitric oxide on oxygenation and pulmonary hemodynamics during acute hypercapnia in acute respiratory failure. DESIGN: Prospective, randomized, experimental study. SETTING: University research laboratory. SUBJECTS: Ten piglets, weighing 9 to 13 kg. INTERVENTIONS: Acute respiratory failure was induced by oleic acid infusion and ...

BACKGROUND: Essential hypertension is associated with impaired endothelium-dependent vasodilation. Inactivation of endothelium-derived nitric oxide by oxygen free radicals participates in endothelial dysfunction in experimental hypertension. To test this hypothesis in humans, we evaluated the effect of antioxidant vitamin C on endothelium-dependent responses in essential hypertensive patients. METHODS AND RESULTS: In ...

To the best of our knowledge, no case of ether-induced acute respiratory distress syndrome (ARDS) has been published as yet. A 36-year-old female developed pneumonitis which showed all the characteristics of a chemical-associated ARDS due to intravenous self-administration of ether: the hemodynamic investigation demonstrated a normal blood flow pattern with ...

In this study, we aimed to elucidate the effects of intrinsic nitric oxide (NO) on cardiac neural regulation. Twenty-two cats were anesthetized with 1.5% isoflurane and allocated to Group I (intact; n = 7), Group D (denervated baroreceptors and vagi; n = 8), or Group B (autonomic blockade with i.v. ...

It has been suggested that inhibitors of nitric oxide synthesis are of value in the treatment of hypotension during sepsis. In this pilot study, we examined the effects of inhibition of nitric oxide synthesis by continuous infusion of N(omega)-nitro-L-arginine methyl ester (L-NAME) at 1.5 mg/kg/h in a patient with severe ...

This study examined the cardiovascular effects of 17beta-estradiol in ovariectomized rats with heart failure. Two groups (50-60 days old) were implanted with 60-day-release pellets containing 17beta-estradiol (25 microg/day) or vehicle at 7 days before ligation of the left coronary artery. Another group was sham operated and given vehicle pellets. After ...

Changes in mean arterial pressure were monitored in rats following 50% isovolemic exchange transfusion with solutions of chemically modified hemoglobins. Blood pressure responses fall into three categories: 1) an immediate and sustained increase, 2) an immediate yet transient increase, or 3) no significant change either during or subsequent to exchange ...

OBJECTIVE: Impaired cholinergic vasodilatation in the forearm in hypertension and hypercholesterolemia has been attributed to impaired nitric oxide bioavailability. However, inhibition of cyclooxygenase reverses the impaired cholinergic dilatation in hypertensive animals and patients. The aim of this study was to examine the effect of aspirin on cholinergic vasodilatation in hypercholesterolemic ...

We studied the differences between isosorbide dinitrate (ISDN) and L-arginine (L-Arg), the precursor of nitric oxide, regarding autonomic nervous function by assessing changes in heart rate variability and blood levels of various vasoactive substances. Healthy volunteers received infused L-arginine (L-Arg group) or isosorbide dinitrate (ISDN group). ECGs were monitored and ...

OBJECTIVE: We sought to describe the effects of ouabain on the human uteroplacental vasculature. STUDY DESIGN: Stem villous vessels and intramyometrial arteries isolated from placental and myometrial biopsy specimens at term were mounted in organ baths. Moreover, isolated human placental cotyledons were perfused. RESULTS: Contractions induced by the thromboxane A2 ...

The central roles of nitric oxide (NO) in regulations of the blood pressure and heart rate were examined in anesthetized rats. Intracerebroventricular (i.c.v.) injection of Nomega-nitro-L-arginine methyl ester (L-NAME) caused dose-dependent increase in the blood pressure and heart rate. The pressor response of the blood pressure to L-NAME (2 micromol, ...

Impaired right-ventricular function may benefit from afterload reduction. Inhalation of nitric oxide (NO) reduces pulmonary hypertension without systemic circulatory depression. Influence of NO inhalation on oxygenation, ventilation, and hemodynamic parameters in 10 patients with acute pulmonary hypertension after cardiac surgery was examined in this study. Ten patients without NO treatment ...

BACKGROUND: Essential hypertension is characterized by an impairment of endothelium-dependent vasodilatation. OBJECTIVE: To test whether antihypertensive treatment with the angiotensin converting enzyme inhibitor lisinopril can improve vasodilatation in response to endothelium-dependent agonists in essential hypertensive patients. DESIGN AND METHODS: We studied the effect of acute (6-8 h after dosing), prolonged ...

BACKGROUND: The role of nitric oxide (NO) in regulation of systemic blood pressure both in normotensives and in hypertensives remains unknown. OBJECTIVE: To investigate the influence of L-arginine (the substrate for generation of NO) on blood pressure in 30 men (aged 51.5 +/- 7.3 years) with established primary arterial hypertension ...