Search results for "Nitroprusside"
showing 10 items of 68 documents
Demonstration of action-potential-producing cells in the rat pineal gland in vitro and their regulation by norepinephrine and nitric oxide
1998
There is evidence that sympathetically innervated mammalian pineal glands contain cells that exhibit action potentials. It is unknown whether ex vivo pineal glands deprived of their nervous input are still capable of firing. In the present study, multiple-unit recordings from rat pineals revealed spontaneously active cell clusters with a mean firing frequency of 1.5 +/- 0.3 Hz which could be abolished by tedrodotoxin. Regularly firing clusters showed no inherent periodicity in the minute range, whereas rhythmical clusters with periodically repeated bursts had period lengths of 12.6 min (day) and 9.5 min (night). Superfusion of norepinephrine reduced the firing frequency of both cluster type…
Role of M1, M3, and M5 muscarinic acetylcholine receptors in cholinergic dilation of small arteries studied with gene-targeted mice
2011
Acetylcholine regulates perfusion of numerous organs via changes in local blood flow involving muscarinic receptor-induced release of vasorelaxing agents from the endothelium. The purpose of the present study was to determine the role of M1, M3, and M5 muscarinic acetylcholine receptors in vasodilation of small arteries using gene-targeted mice deficient in either of the three receptor subtypes (M1R−/−, M3R−/−, or M5R−/− mice, respectively). Muscarinic receptor gene expression was determined in murine cutaneous, skeletal muscle, and renal interlobar arteries using real-time PCR. Moreover, respective arteries from M1R−/−, M3R−/−, M5R−/−, and wild-type mice were isolated, cannulated with mic…
Ca2+-activated K+ channels mediate relaxation of forearm veins in chronic renal failure
2003
In arteries, agonists such as acetylcholine release an endothelium-derived hyperpolarizing factor (EDHF) that is neither nitric oxide nor prostacyclin.To examine the responses to acetylcholine in segments of forearm veins from patients with chronic renal failure who either had never received dialysis or had undergone long-term dialysis, and to determine the contribution of nitric oxide and EDHF to endothelium-dependent relaxation in veins from patients with chronic renal failure.Isometric tension was recorded in rings of forearm vein from 34 non-dialysed patients, 27 dialysed patients and 14 multiorgan donors (controls).Relaxation in response to acetylcholine was reduced in veins of non-dia…
Nitric oxide as neuromodulator of sympathetic transmission in rat vas deferens.
1998
Summary Electrical field stimulation (EFS) of muscle strips in vitro elicited a tetrodotoxin (TTX)-sensitive biphasic contractile response consisting of a phasic component followed by a tonic one. The amplitude of both components of the response was impaired by Nω-nitro-L-arginine and potentiated by sodium nitroprusside. Cystamine caused a reduction in amplitude of both phasic and tonic componets of the response to EFS. Neither Nω-nitro-L-arginine, sodium nitroprusside, nor cystamine induced changes in the resting muscle tone, or in the contractile response to exogenous agonists ATP and noradrenaline (NA). The nitric oxide scavenger, 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide, i…
Nitric oxide inhibits electrically active units in the rat pineal gland.
1997
Extracellular multiple unit recordings were performed in isolated rat pineal glands to determine a possible effect of nitric oxide (NO) on the spontaneous electrical activity of pinealocytes. Spontaneously active cells forming clusters of 3-5 cells fell into two categories: more or less regularly firing clusters (REG, 64%) and irregularly discharging clusters with periodically repeated bursts (RHY, 36%). The NO-donor sodium nitroprusside (SNP) reduced the discharge rate of the great majority of REG clusters and of all the RHY clusters examined. Moreover, the burst activity of RHY clusters was abolished. These results could be completely reproduced by using another NO-donor, S-nitroso-N-acet…
Comparative relaxant effects of the NO donors sodium nitroprusside, DEA/NO and SPER/NO in rabbit carotid arteries.
1999
1. Sodium nitroprusside (SNP, 10(-9)-3x10(-4) M), diethylamine/NO complex (DEA/NO, 10(-9)-10(-4) M) and spermine/NO complex (SPER/NO, 10(-8)-3x10(-4) M) induced concentration-dependent relaxation of isolated rabbit carotid arteries precontracted with KCl (50 mM) or with histamine (3x10(-6) M). 2. In KCl-precontracted arteries the order of potency was SNP=DEA/NO>SPER/NO, and in histamine-precontracted arteries the order of potency was SNP>DEA/NO>SPER/NO. Relaxations to the three NO donors were significantly higher in histamine-precontracted arteries than in KCl-precontracted arteries. 3. The guanylyl cyclase inhibitor methylene blue (10(-5) M) significantly inhibited relaxations to the three…
Inducible NO synthase confers chemoresistance in head and neck cancer by modulating survivin
2009
The dual role of the inducible NO synthase (iNOS) and NO signaling in head and neck squamous cell carcinoma (HNSCC) is a complex and can both promote or inhibit tumor progression. However, the underlying molecular mechanisms are not yet resolved in detail. We show for the first time that conditions, favoring low NO levels conferred resistance against cisplatin/taxol-induced apoptosis in HNSCC cell lines. Cytoprotection was mediated by survivin, because we observed its upregulation subsequent to low doses of the NO donors S-nitroso-N-acetyl-penicillamine (SNAP) and sodium nitroprusside (SNP) or ectopic expression of physiologic amounts of iNOS. Also, RNAi-mediated depletion of survivin block…
The Janus face of chlorogenic acid on vascular reactivity: A study on rat isolated vessels
2016
Abstract Background Chlorogenic acid (CGA), the main polyphenol contained in coffee, is a major contributor to dietary polyphenol intake. Few studies reported its anti-hypertensive properties but the mechanisms are still indefinite. Purpose The present study assessed the direct effect of CGA in endothelium denuded or intact aortic rings from male Wistar rats and the mechanisms involved. Methods/Results CGA induced a direct endothelium-dependent relaxation that was significantly reduced by L-NAME (10 −4 M), indomethacin (10 −5 M) and combination of apamin (10 −7 M) and charybdotoxin (10 −7 M). Incubation of rings with CGA induced a dual effect on agonist-induced vasorelaxation. At 10 −6 …
Interplay between PACAP and NO in mouse ileum
2003
Abstract We investigated the possibility that pituitary adenylate cyclase activating peptide (PACAP) has a role in the control of contractility in the mouse ileum. PACAP-(1-27) produced tetrodotoxin (TTX)-insensitive, concentration-dependent reduction of the amplitude of the spontaneous contractions of longitudinal muscle up to their complete disappearance. This effect was inhibited by PACAP-(6-38), PACAP receptor antagonist, and by apamin, blocker of small-conductance Ca2+-activated K+-channels. Nω-nitro- l -arginine methyl ester (L-NAME), nitric oxide (NO) synthase inhibitor, reduced the PACAP-inhibitory response, and the joint application of apamin plus L-NAME produced additive effects. …
Differential effects of nitric oxide donors on basal and electrically evoked release of acetylcholine from guinea-pig myenteric neurones
1996
1. The effects of the nitric oxide (NO) donors, 3-morpholino-sydnonimine (SIN-1), S-nitroso-N-acetylpenicillamine (SNAP) and sodium nitroprusside on basal and electrically evoked release of [3H]-acetylcholine were studied in myenteric plexus longitudinal muscle preparations of the guinea-pig small intestine preincubated with [3H]-choline. 2. The NO donors concentration-dependently increased basal release of [3H]-acetylcholine. The increase in release was calcium-dependent and was prevented in the presence of tetrodotoxin. Superoxide dismutase (150 u ml-1) potentiated the effect of SIN-1. The selective inhibitor of soluble guanylyl cyclase, 1H-[1,2,4]oxadiazolo[4,3-alpha]quinoxalin-1-one (OD…