Search results for "Nitroprusside"
showing 10 items of 68 documents
The Oxidative Stress Concept of Nitrate Tolerance and the Antioxidant Properties of Hydralazine
2005
The hemodynamic and anti-ischemic effects of nitroglycerin (NTG) are rapidly blunted as a result of the development of nitrate tolerance. With initiation of NTG therapy, it is possible to detect neurohormonal activation and intravascular volume expansion. These so-called pseudotolerance mechanisms may compromise the vasodilatory effects of NTG. Long-term nitrate treatment also is associated with decreased vascular responsiveness caused by changes in intrinsic mechanisms of the tolerant vasculature itself. According to the oxidative stress concept, increased vascular superoxide (O 2 − ) production and an increased sensitivity to vasoconstrictors secondary to activation of protein kinase C co…
Relaxant effect of sildenafil in the rabbit basilar artery
2005
We hypothesized that sildenafil, inhibitor of phosphodiesterase-5 (PDE-5), interacts with the nitric oxide (NO)-cGMP pathway in the cerebral arteries and shows vasoactive effects. To prove it in the isolated rabbit basilar artery, we compared the effects of sildenafil with other PDE-5 inhibitors, assessed the endothelial dependence of the vasoactive responses, and used modulators of the cGMP and cAMP signaling processes. Sildenafil (10 nM-0.1 mM) induced concentration-dependent relaxations of endothelin-1 (10 nM)-precontracted basilar artery, which were partially inhibited both in endothelium-denuded arteries and in arteries precontracted by depolarization with KCl (50 mM). Endothelin-1 (1 …
Increased responsiveness of human pulmonary arteries in patients with positive bronchodilator response.
1996
Abstract 1. The effects of noradrenaline, endothelin-1, acetylcholine and sodium nitroprusside were studied in isolated pulmonary arteries obtained from 14 patients undergoing lobectomy for lung carcinoma. Seven patients had shown increased response to a bronchodilator test prior to operation. In the remaining patients (control) the bronchodilator test was negative. 2. Artery rings from patients with a positive bronchodilator response showed greater contraction to noradrenaline (pD2 = 6.44 +/- 0.1; Emax = 93 +/- 9% of response to 100 mM KCl) and endothelin-1 (pD2 = 8.92 +/- 0.1; Emax = 130 +/- 16%) than the rings from control patients (pD2 = 6.04 +/- 0.08; Emax = 56 +/- 8% for noradrenaline…
Evidence for a role of inducible nitric oxide synthase in gastric relaxation of mdx mice
2006
Alterations of gastric mechanical activity have been reported in mdx mouse, animal model for Duchenne muscular dystrophy. This study examined if alterations in the vasoactive intestinal polypeptide (VIP) system are present in mdx stomach. Gastric mechanical activity was recorded in vitro as changes of endoluminal pressure and neurally or pharmacologically evoked relaxations were analysed in mdxvs normal stomach. Reverse-transcription polymerase chain reaction was used to detect inducible nitric oxide synthase (iNOS) expression. Relaxations to sodium nitroprusside in mdx stomach showed no difference in comparison with normal preparations. In normal stomach, VIP produced relaxation, which was…
Retracted: Cerebral effects and blood sparing efficiency of sodium nitroprusside-induced hypotension alone and in combination with acute normovolaemi…
2001
The combined reduction of oxygen-carrying capacity and perfusion pressure during the combination of acute normovolaemic haemodilution (ANH) and controlled hypotension (CH) raises concerns of hypoperfusion and ischaemic injury to the brain. Forty-two patients undergoing radical prostatectomy were prospectively allocated to receive CH induced by sodium nitroprusside (mean arterial pressure (MAP) 50 mm Hg), a combination of CH+ANH (post-ANH haematocrit 29%; intraoperative MAP 50 mm Hg), or standard anaesthesia (control). Serum levels of the brain-originated proteins neuron-specific enolase (NSE) and protein S-100, blood loss, transfusion requirements, adverse effects, and postoperative recover…
Aging-related endothelial dysfunction in the aorta from female senescence-accelerated mice is associated with decreased nitric oxide synthase express…
2013
The present study investigated the time-course for aging-associated effects on contractile and relaxing vascular responses and nitric oxide (NO) production in the aorta from female senescence-accelerated resistant (SAMR1) and prone (SAMP8) mice. Both SAMR1 and SAMP8 were studied at three different ages: 3 (young), 6 (middle age) and 10 (old) months. Concentration-response curves to phenylephrine (10(-8) to 10(-5) M) or acetylcholine (10(-9) to 10(-5) M) were performed in the aortic rings in the absence or in the presence of NO synthase (NOS) inhibitor L-NAME (10(-4) M). Protein and gene expression for endothelial NOS (eNOS) was determined by immunofluorescence, Western blot and real-time PC…
Relaxant effects of sodium nitroprusside and NONOates in goat middle cerebral artery: delayed impairment by global ischemia-reperfusion.
1999
Global cerebral ischemia and subsequent reperfusion induce early impairment of the vasodilator responses to hypercapnia and vasoactive substances. Nitric oxide (NO) is involved in the regulation of cerebral blood flow (CBF) in both health and disease. The present study was designed to assess possible changes in the cerebrovascular reactivity to NO donors induced by cerebral ischemia-reperfusion in goats. Female goats (n = 9) were subjected to 20 min global cerebral ischemia under halothane/N2O anesthesia. Sixteen additional goats were sham-operated as a control group. One week later the effects of ischemia-reperfusion on relaxations to NO donors sodium nitroprusside (SNP), diethylamine/NO (…
Effects of ouabain on human bronchial muscle in vitro
2003
The effects of ouabain, an inhibitor of the plasmalemmal Na(+)/K(+)-ATPase activity, were examined in human isolated bronchus. Ouabain produced concentration-dependent contraction with -logEC(50)=7.16+/-0.11 and maximal effect of 67+/-4% of the response to acetylcholine (1 mM). Ouabain (10 microM)-induced contraction was epithelium-independent and was not depressed by inhibitors of cyclooxygenase and lipoxygenase, antagonists of muscarinic, histamine H(1)-receptors and alpha-adrenoceptors, or neuronal Na(+) channel blockade. The inhibition of ouabain contraction in tissues bathed in K(+)-free medium, and the inhibition by ouabain of the K(+)-induced relaxation confirm that the contractile a…
Development of a polydimethylsiloxane–thymol/nitroprusside composite based sensor involving thymol derivatization for ammonium monitoring in water sa…
2014
This report describes a polydimethylsiloxane (PDMS)-thymol/nitroprusside delivery composite sensor for direct monitoring of ammonium in environmental water samples. The sensor is based on a PDMS support that contains the Berthelot's reaction reagents. To prepare the PDMS-thymol/nitroprusside composite discs, thymol and nitroprusside have been encapsulated in the PDMS matrix, forming a reagent release support which significantly simplifies the analytical measurements, since it avoids the need to prepare derivatizing reagents and sample handling is reduced to the sampling step. When, the PDMS-thymol/nitroprusside composite was introduced in water samples spontaneous release of the chromophore…
Deliberate Arterial Hypotension Does Not Reduce Intraocular Pressure in Pigs
1992
Among the accepted advantages of general anesthesia in ophthalmic surgery is improved control of intraocular pressure (IOP). Although standard textbooks advocate deliberate arterial hypotension to facilitate intraocular surgery by reducing IOP, scientific proof of such an effect is lacking. The authors investigated effects of induced arterial hypotension on IOP in an anesthetized porcine model. Forty-two piglets were anesthetized with piritramide, were placed in the prone position, and had the anterior chamber of one eye punctured with a small Teflon cannula to measure IOP. Six pigs were used in a pilot study to establish dose-response relationships for the hypotensive agents; 36 pigs were …