N-Acetylcysteine Enhances Endothelium-Dependent Vasorelaxation in the Isolated Rat Mesenteric Artery

doi:10.1016/S0196-0644(98)70167-2

Annals of Emergency Medicine

Volume 32, Issue 4, October 1998, Pages 405-410

Presented at the Society for Academic Emergency Annual Meeting, Washington DC, May 1997.

https://doi.org/10.1016/S0196-0644(98)70167-2 Get rights and content

Abstract

Study Hypothesis: Previous studies have suggested that N-Acetylcysteine (NAC) may confer additional protection in acetaminophen (APAP) overdose by improving hepatic microcirculation. We hypothesize that NAC enhances release of nitric oxide (NO) from the vasculature. Methods: Sprague-Dawley rat superior mesenteric artery rings were suspended in oxygenated Krebs-Henseleit tissue baths and contracted with U-46619 (a thromboxane A₂ -mimetic). In part 1, the effect of NAC on endothelial cell (EC) release of NO was assessed by measurement of vasorelaxation induced by acetylcholine (ACh, an EC-dependent vasorelaxor) in the presence and absence of NAC. In part 2, the effect of glutathione (a major component of NAC hepatoprotection) was examined by measuring ACh-induced vasorelaxation in rings from rats treated with l-buthionine sulfoxamine (BSO, a glutathione synthesis inhibitor). Data were analyzed by repeated-measures ANOVA. Results: Addition of 15 to 30 mmol/L NAC after ring contraction had no direct vasodilatory effect. By contrast, pretreatment of rings with NAC (15 mmol/L) enhanced vasorelaxation induced by ACh (95.0%±7.9% versus 62.3%±7.6% for control; ACh dose, 1 μmol/L; P<.001) or by A23187, a receptor-independent, NO-mediated vasodilator (91.6%±9.6% versus 68.3%±12.1% for control; A23187 dose, 1 μmol/L; P<.001). In rings from BSO-treated rats, NAC also enhanced vasorelaxation (76.5%±7.1%; P<.001 versus control), but to a lesser degree than in nontreated rats. Conclusion: NAC enhances endothelium-dependent vasodilation in an isolated rat mesenteric artery ring preparation. In addition to its antioxidant effects, NAC may decrease APAP hepatotoxicity by stimulating NO production and improving microvascular circulation.[Lopez BL, Snyder JW, Birenbaum DS, Ma X-l: N-Acetylcysteine enhances endothelium-dependent vasorelaxation in the isolated rat mesenteric artery. Ann Emerg Med October 1998;32:405-410.]

Section snippets

INTRODUCTION

The biotransformation of acetaminophen (APAP) in the overdose setting produces excessive amounts of N -acetyl-p -benzoquinoneimine (NAPQI), which is thought to be the major toxic intermediate.¹ N -acetylcysteine (NAC) is the treatment of choice for acute APAP overdose. Proposed mechanisms of protection by NAC include (1) prevention of binding of NAPQI to hepatocytes, (2) increased synthesis of glutathione and sulfate, (3) direct binding of NAC to NAPQI, and (4) increased reduction of NAPQI to

MATERIALS AND METHODS

This study was approved by the Animal Care and Use Committee of Thomas Jefferson University. Superior mesenteric artery (SMA) rings were prepared as follows. Male Sprague-Dawley rats (250 to 300 g each) were sacrificed after anesthesia with intraperitoneal sodium pentobarbital (50 mg/kg). Each rat yielded 3 to 4 SMA rings for study. The SMAs were carefully removed and placed into ice-cold Krebs-Henseleit buffer consisting of the following (in mmol/L): NaCl, 118; KCl, 4.75; CaCl₂ ·2H₂ O, 2.54; KH

RESULTS

Figure 1 demonstrates that direct administration of progressively higher concentrations of NAC had no vasodilatory effect.

. Time course of representative contraction force recordings from vascular rings. Dots represent addition of progressively higher concentrations of ACh (1, 10, 100, 1,000, and 10,000 nmol/L) and NAC (5, 10, 15, 30 mmol/L).

By contrast, Figure 2 shows that incubation of rings with NAC induced greater vasorelaxation, shifting the ACh-induced vasorelaxation curve to the left.

DISCUSSION

APAP overdose may result in formation of the putative toxic metabolite NAPQI. Detoxification of NAPQI may deplete hepatic glutathione. Once glutathione stores fall below 30% of normal, NAPQI may initiate events that contribute to loss of hepatocyte viability.²⁵

NAC is the treatment of choice for acute APAP overdose. NAC may provide a substrate for glutathione synthesis, or it may directly reduce NAPQI to a nontoxic cysteine conjugate. NAC also may supply substrate for sulfation, increasing the

References (31)

R Esterline et al.
Reversible and irreversible inhibition of hepatic mitochondrial respiration of acetaminophen and its toxic metabolite, N -acetyl-p -benzoquinoneimine (NAPQI)
Biochem Pharmacol
(1989)
JB Hibbs et al.
Nitric oxide: A cytotoxic-activated macrophage effector molecule
Biochem Biophys Res Commun
(1988)
S Moncada et al.
Endothelium derived relaxing factor: Identification as nitric oxide and role in the control of vascular tone and platelet function
Biochem Pharmacol
(1988)
A Meister
Glutathione metabolism
Methods Enzymol
(1995)
MW Radomski et al.
Endogenous nitric oxide inhibits human platelet adhesion to vascular endothelium
Lancet
(1987)
H Kobayashi et al.
Role of endogenous nitric oxide in ischemia-reperfusion injury in rat liver
J Surg Res
(1995)
DR Arnelle et al.
NO+, NO, and NO– donation by s -nitrosothiols: Implications for regulation of physiological functions by s-nitrosylation and acceleration of disulfide formation
Arch Biochem Biophys
(1995)
BH Lauterburg et al.
Mechanism of action of N -acetylcysteine in the protection against the hepatotoxicity in rats in vivo
J Clin Invest
(1983)
PM Harrison et al.
Improved outcome of paracetamol-induced fulminant hepatic failure by late administration of acetylcysteine
Lancet
(1990)
R Keays et al.
Intravenous acetylcysteine in paracetamol induced fulminant hepatic failure: A prospective controlled trial
Br Med J
(1991)

PM Harrison et al.

Improvement by acetylcysteine of hemodynamics and oxygen transport in fulminant hepatic failure

N Engl J Med

(1991)

JM Rappeport et al.

Bone marrow failure: Aplastic anemia and other primary bone marrow disorders

LJ Ignarro et al.

Endothelium-derived relaxing factor produced and released from artery and vein is nitric oxide

Proc Natl Acad Sci U S A

(1987)

GM Rubanyi et al.

Superoxide anions and hyperoxia inactivate endothelium-derived relaxing factor

Am J Physiol

(1986)

P Lopez-Jarmillo et al.

The crucial role of physiologic Ca²⁺ concentrations in the production of endothelial nitric oxide and the control of vascular tone

Br J Pharmacol

(1990)

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In our previous study we showed the occurrence of lipid peroxidation in the PFC, HC and ST of female periadolescent NIC-kindled rats, but not in male ones, this alteration being prevented by vitamin E. Besides NAC's antioxidant effects, this drug acts as a vasodilator by facilitating the production and action of NO (Lopez et al. 1998). Increases in the activity of brain neuronal NO synthase were observed in normotensive and hypertensive animals chronically administrated NAC (Pechanova et al. 2009).
Kindling is a form of behavioral sensitization that is related to the progression of several neuropsychiatric disorders such as bipolar disorder. We recently demonstrated that female periadolescent rats are more vulnerable to nicotine (NIC)-induced kindling than their male counterparts. Furthermore, we evidenced that decreases in brain antioxidative defenses may contribute to this gender difference. Here we aimed to determine the preventive effects of the antioxidant N-acetyl cysteine (NAC) against NIC-kindling in female periadolescent rats. To do this female Wistar rats at postnatal day 30 received repeated injections of NIC 2 mg/kg, i.p. every weekday for up to 19 days. NAC90, 180 or 270 mg/kg, i.p. was administered 30 min before NIC. The levels of glutathione (GSH), superoxide dismutase (SOD) activity, lipid peroxidation (LP) and nitrite were determined in the prefrontal cortex (PFC), hippocampus (HC) and striatum (ST). The development of kindling occurred at a median time of 16.5 days with 87.5% of NIC animals presenting stage 5 seizures in the last day of drug administration. NAC270 prevented the occurrence of kindling. NIC-kindled animals presented decreased levels of GSH and increased LP in the PFC, HC and ST, while SOD activity was decreased in the ST. NAC180 or 270 prevented the alterations in GSH induced by NIC, but only NAC270 prevented the alterations in LP. Nitrite levels increased in the ST of NAC270 pretreated NIC-kindled animals. Taken together we demonstrated that NAC presents anti-kindling effects in female animals partially through the restoration of oxidative alterations.
Glutathione monoethyl ester improves functional recovery, enhances neuron survival, and stabilizes spinal cord blood flow after spinal cord injury in rats
2005, Neuroscience
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These observations suggest that both MPSS and GSHE cause local vasodilation of SC blood vessels. Like GSH, its precursor GSHE could exert its effect on SCBF by improving endothelial function altered by oxidative stress (Lopez et al., 1998; Prasad et al., 1999; Weiss et al., 2001; Arosio et al., 2002). GSH causes vasodilation and therefore improvement of macro- and microcirculation, by reacting with peroxynitrite to form S-nitrosoglutathione, thereby increasing nitric oxide levels which in turn activate nitric oxide-guanylate cyclase-dependent mechanisms (Cheung and Schulz, 1997).
Secondary damage after spinal cord (SC) injury remains without a clinically effective drug treatment. To explore the neuroprotective effects of cell-permeable reduced glutathione monoethyl ester (GSHE), rats subjected to SC contusion using the New York University impactor were randomly assigned to receive intraperitoneally GSHE (total dose of 12 mg/kg), methylprednisolone sodium succinate (total dose of 120 mg/kg), or saline solution as vehicle. Motor function, assessed using the Basso–Beattie–Bresnahan scale for 8 weeks, was significantly better in GSHE (11.2±0.6, mean±S.E.M., n=8, at 8 weeks) than methylprednisolone (9.3±0.6) and vehicle (9.4±0.7) groups. The number of neurons in the red nuclei labeled with FluoroRuby placed caudally to the injury site was significantly higher in GSHE (158±9.3 mean±S.E.M., n=4) compared with methylprednisolone (53±14.7) and vehicle (46±16.4) groups. Differences in the amount of spared SC tissue at the epicenter and neighboring areas were not significant among experimental groups. In a second series of experiments, using similar treatment groups (n=6), regional changes in microvascular SC blood flow were evaluated for 100 min by laser-Doppler flowmetry after clip compression injury. SC blood flow fell in vehicle-treated rats 20% below baseline and increased significantly with methylprednisolone approximately 12% above baseline; changes were not greater than 5% in rats given GSHE. In conclusion, GSHE given to rats early after moderate SC contusion/compression improves functional outcome and red nuclei neuron survival significantly better than methylprednisolone and vehicle, and stabilizes SC blood flow. These results support further investigation of reduced glutathione supplementation after acute SC injury for future clinical application.
Free radical scavengers improve the impaired endothelium-dependent responses in aorta and kidneys of diabetic rabbits
2003, Diabetes Research and Clinical Practice
The effects of two endogenous antioxidants, α-lipoic acid and reduced gluthathione (GSH), were evaluated in the response of the renal vasculature and aortic rings ex vivo of 4-week alloxan-diabetic rabbits to the endothelium-dependent agonists bradykinin (BK) and acetylcholine (Ach) or to the endothelium-independent agonist sodium nitroprusside (SNP) and compared with age and sex-matched euglycemic rabbits. The maximal decrease in perfusion pressure (R_max) after BK infusion in the renal vasculature from diabetic rabbits was 5.4±1.3% (PD₂ 8 [12.6−3.4]) compared with 34.2±4.2% (PD₂ 9 [11.3−6.7]) (P<0.05) attained in tissues obtained from euglycemic rabbits. The addition of 1 μM lipoic acid or GSH improved (P<0.05) the R_max to BK to 18.3±2.4% (PD₂ 8.6 [12.4−4.8]) and 19.5±3.7% (PD₂ 9.1 [13.3−4.9]), respectively. Similarly, the maximal vasorelaxant response to Ach in kidneys from diabetic rabbits was 16±2.0% (PD₂ 7.3 [10.4−4.2] whilst the R_max in kidneys from euglycemic animals was 52.7±4.9% (PD₂ 11.3 [16.4−6.2]). Incubation with 1 μM α-lipoic acid or GSH restored the R_max to Ach to 31±3.9% (PD₂ 9.8 [14.3−5.3]) and to 23±5.4% (PD₂ 7.6 [11.4−3.8], respectively. The vasodilatory response to SNP was unaltered among tissues from diabetic and euglycemic rabbits and was also unaffected by the treatments utilized. In addition, the R_max to Ach in aortic rings of diabetic rabbits was 28.7±2.4% (PD₂ 8.3 [11.7−4.9]) compared with 100% (PD₂ 7.9 [12.1−3.7]) obtained in tissues gathered from euglycemic rabbits. The pretreatment of the tissues with α-lipoic acid restores the R_max to 47.4±4% (PD₂ 11.1 [14.3−7.9]) and the pretreatment with GSH to 52±3.2% (PD₂ 9.8 [12.7−6.9]). Similarly, the response to SNP was unaltered in all groups. Lipoic acid and reduced gluthatione directly improved the endothelium-dependent response of renal arterioles and aortic rings of diabetic rabbits.
N-acetylcysteine improves nitric oxide and α-adrenergic pathways in mesenteric beds of spontaneously hypertensive rats
2003, American Journal of Hypertension
The aim of this study was to assess the effects of N-acetylcysteine (NAC) on nitric oxide and adrenergic pathways in mesenteric artery from spontaneously hypertensive rats (SHR) and Wistar-Kyoto rats (WKY).
Rats were treated with 4 gkg⁻¹day⁻¹ of NAC during 4 weeks or mesenteric beds were treated with 10 mmol/L of NAC during 20 min.
In conscious rats, the NAC treatment produced a significant reduction of mean arterial pressure (MAP) and heart rate in SHR (P < .001). N^ω-nitro-l-arginine methyl ester (L-NAME) caused a MAP increase in NAC-treated SHR of magnitude similar to that in WKY, which was significantly higher than that observed in control untreated SHR (P < .05). Chronic treatments with NAC improved the maximal relaxation of mesenteric arteries to A23187 in SHR (P < .001). Acute NAC treatment in vitro induced a vasodilation in Phe preconstricted arteries (P < .001) that was stronger in SHR than in WKY (P < .05) and was not abolished by L-NAME. The vasoconstrictory response and increases in inositol phosphate production induced by superoxide anion were attenuated by NAC treatment through its superoxide scavenging properties. In contrast, chronic and acute NAC treatments did not alter the vasodilatory response to β-adrenergic receptor stimulation.
The increase in NO-mediated vasodilator tone and the possible decrease in adrenergic vasoconstriction induced by NAC treatment in SHR could explain the hypotensive effect of NAC in this model of hypertension.
The role of natural antioxidants in preserving the biological activity of endothelium-derived nitric oxide
2000, Free Radical Biology and Medicine
Endothelium-derived nitric oxide (EDNO) is a pivotal molecule in the regulation of vascular tone via the stimulation of vascular smooth muscle cell relaxation and concomitant vasodilation. In addition, EDNO exerts a number of other potent antiatherogenic effects, including inhibition of leukocyte-endothelial interactions, smooth muscle cell proliferation, and platelet aggregation. Endothelial vasodilator dysfunction has been observed in patients with CAD or coronary risk factors such as hypercholesterolemia, hyperhomocysteinemia, essential hypertension, diabetes mellitus, smoking, and aging. Most of these conditions are associated with increased oxidative stress, particularly increased production of superoxide radicals and elevated levels of oxidized LDL, both of which can attenuate the biological activity of EDNO. The levels of superoxide and oxidized LDL can be decreased by administering the small molecule antioxidants vitamins E and C. Vitamin C also spares intracellular thiols, which in turn can stabilize EDNO through the formation of biologically active S-nitrosothiols. Here we review the role that vitamins E and C and thiol compounds play in endothelium-dependent vasodilation. Understanding the mechanisms of the reversal of endothelial dysfunction by natural antioxidants will lead to successful therapeutic interventions of CAD and its clinical sequelae.
N-acetylcysteine for prevention of acute renal failure in patients with chronic renal insufficiency undergoing cardiac surgery: A prospective, randomized, clinical trial
2008, Critical Care Medicine
To assess the preventive effect of the antioxidant N-acetylcysteine on postoperative acute renal failure in patients with renal insufficiency undergoing cardiac surgery.
Randomized, placebo-controlled, prospective study.
University cardiology center.
Two hundred fifty-four consecutive patients with chronic renal insufficiency (estimated creatinine clearance ≤60 mL/min) undergoing elective cardiac surgery.
Patients were randomized to receive N-acetylcysteine (n = 129) or placebo (n = 125). Patients of the N-acetylcysteine group received four boluses of intravenous N-acetylcysteine (1200 mg every 12 hrs, starting immediately before cardiac surgery).
The incidence of postoperative acute renal failure (>25% increase in serum creatinine from baseline) and the in-hospital clinical course were evaluated. Acute renal failure occurred in 46% of patients and was associated with increased in-hospital mortality (7% vs. 0.7%; p = .024). It occurred in 52% of control patients and 40% of N-acetylcysteine-treated patients (p = .06). In-hospital mortality and need for renal replacement therapy were not affected by N-acetylcysteine, but a lower percentage of N-acetylcysteine-treated patients required mechanical ventilation prolonged for >48 hrs (3% vs. 18%; p < .001) and had an intensive care unit stay >4 days (13% vs. 33%; p < .001).
Intravenous administration of N-acetylcysteine does not clearly prevent postoperative acute renal failure in patients with renal insufficiency undergoing cardiac surgery.

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^☆: From the Division of Emergency Medicine, Department of Surgery, Jefferson Medical College, Philadelphia, PA.

^☆☆: Reprint no. 47/1/92815

^★: Address for reprints: Bernard L Lopez, MD, Jefferson Medical College, Division of Emergency Medicine, 1020 Walnut Street, Philadelphia, PA 19107, E-mail [email protected]

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N-Acetylcysteine Enhances Endothelium-Dependent Vasorelaxation in the Isolated Rat Mesenteric Artery☆,☆☆,★

Abstract

Section snippets

INTRODUCTION

MATERIALS AND METHODS

RESULTS

DISCUSSION

Biochem Pharmacol

Biochem Biophys Res Commun

Biochem Pharmacol

Methods Enzymol

Lancet

J Surg Res

Arch Biochem Biophys

Mechanism of action of N -acetylcysteine in the protection against the hepatotoxicity in rats in vivo

J Clin Invest

Improved outcome of paracetamol-induced fulminant hepatic failure by late administration of acetylcysteine