SHA24/036004

‫بسم ا الرحمن الرحيم‬

Cairo University Faculty of Pharmacy Department of Pharmacology & Toxicology

Effect of magnesium supplementation on metabolic energy changes in lipopolysaccharide-induced cardiotoxicity in mice

Introduction

Lipopolysaccharide (LPS), a gram-negative bacterial endotoxin, is a major factor that

contributes to morbidity and mortality in critically ill patients in intensive care units In sepsis, a number of metabolic abnormalities contribute to serious bioenergetic failure and subsequent multiple organ dysfunction

These metabolic abnormalities include

ROS overproduction

Antioxidant systems depletion

The heart is more susceptible to oxidative stress due to: Oxidative stress • Its higher oxygen consumption •Relatively lower levels of antioxidant enzyme activity than the other tissues Impaired mitochondrial energy production

Previously mentioned oxidative stress and energy failure

• Cardiomyocyte hypertrophy • Apoptosis • Interstitial fibrosis • Progression of cardiac failure

Magnesium is a well known cofactor in many enzymatic reactions that are central to energy creation and utilization

Magnesium plays an important role in the maintenance of adequate electrophysiology and function of cardiomyocytes

THERAPEUTIC EFFECTS OF MAGNESIUM IN CARDIOVASCULAR DISEASES •Suppression of arrhythmias

•Increased coronary blood flow •Inhibition of platelet aggregation

• Decreased peripheral vascular disease • Ion stabilizing effect

• Improvement of mitochondrial energy production

Aim of the Work This study was directed to estimate the protective effects of magnesium supplementation on metabolic energy and mitochondrial ultrastructural changes induced by LPS cardiotoxicity in mice.

Experimental Work

Animals: Adult male albino mice weighing 22-28 g

Chemicals and Drugs •Endotoxin lipopolysaccharide (LPS) from Escherichia coli serotype (055: B5) • Magnesium aspartate

Groups 1stgroup

Normal group

2nd group

LPS group (2 mg/kg,i.p.)

1 h after last dose

3rd group

LPS

Mg (20 mg/kg/day for 7 days) 1 h after last dose

4 group th

Mg (40 mg/kg/day for 7 days)

LPS

Measured Parameters

Three hrs after LPS injection I) Rectal temperature II) Hemodynamic parameters Heart rate (HR)

III) Biochemical parameters

Tissue • Anaerobic Lactate andglycolysis pyruvate

Plasma • Myocardial CK-MB activity damage

• Energy of cell& Adenine nucleotides Creatinecharge phosphate • Oxidative TBARS and stress GSH contents •Na Ionic K ATPase gradient maintenance

IV) Hisological examination Electron microscopic examination for mitochondria and myofibrils

Results

Table (I): Effect of Mg administration on LPSinduced changes in body temperature and heart rate in mice Temperature (oC)

Heart rate (beats/min)

Normal

36.64 ± 0.60

270.86 ± 4.45

LPS

39.21 ± 0.17 *

306.43 ± 9.38 *

Mg (lower dose)

36.08 ± 0.17 @

300.86 ± 8.12 *

Mg (higher dose)

35.86 ± 0.25 @

274.67 ± 4.39 @

Groups

Each value represents the mean of 5-7 experiments ± S.E.M. ∗p<0.05 vs. normal, @p<0.05 vs. LPS.

Table (II): Effect of Mg administration on LPS-induced changes in myocardial CP, adenine nucleotides and Na K ATPase activity in mice

Groups Normal LPS Mg (lower dose) Mg (higher dose)

CP (µmol/g wt tissue)

ATP (µmol/g wt tissue)

ADP (µmol/g wt tissue)

ATP/ADP

Na K ATPase (µmol/ Pi/h/mg protein)

21.04 ± 0.78 12.5 ± 0.77 *

12.02 ± 0.57 6.08 ± 0.62 *

2.08 ± 0.33 3.88 ± 0..49 *

6.11 ± 0.54 1.6 ± 0.16 *

23.72 ± 0.94 7.87 ± 0.76 *

13.3 ± 1.23 *

5.78 ± 0.44 *

2.27 ± 0.18 @

2.53 ± 0.20 *

12.74 ± 0.91 *

19.12 ± 1.83 @

8.44 ± 0.48 *, @

1.78 ± 0.16 @

4.80 ± 0.19 *, @

16.66 ± 0.45 @

Each value represents the mean of 5-7 experiments ± S.E.M. * p<0.05 vs. normal, @p<0.05 vs. LPS.

As a marker membrane damage

*

*

@

Figure (1): Effect of Mg administration on LPS-induced changes in plasma CK-MB in mice.

Each value represents the mean of 5-7 experiments Âą S.E.M. *p<0.05 vs. normal, @p<0.05 vs. LPS.

As markers for oxidative stress @ @

A *

*

**

@ @

@

B

Figure (2): Effect of Mg administration on LPS-induced changes in myocardial GSH (A) and TBARS (B) in mice.

Each value represents the mean of 5-7 experiments Âą S.E.M. *p<0.05 vs. normal, @p<0.05 vs. LPS.

As a marker for intracellular acidosis * *

C

,@

A

@

*

*, @ @ @

B

@

*

Figure (3): Effect of Mg administration on LPS-induced changes in myocardial lactate (A), pyruvate (B) and lactate/pyruvate ratio (C) in mice.

Each value represents the mean of 5-7 experiments Âą S.E.M. *p<0.05 vs. normal, @p<0.05 vs. LPS.

B

A

m

m

D

C

m m

Figure (4): Electron microscopic ultrastructural examination of myocardial damage (magnification x 10,000).

A= normal

B= LPS

C= Mg (20 mg/kg)

D= Mg (40 mg/kg)

CONCLUSIONS

•Magnesium therapy could be a reliable protective agent in LPS induced cardiotoxicity.

•Higher dose of magnesium therapy was more effective in reducing cell membrane damage as well as in improving the intracellular acidosis, energy production, oxidative stress, Na K ATPase activity.

•Mitochondrial ultrastructure examination revealed better improvement by the higher dose of magnesium compared to LPS group.

•Finally, clinical studies are required to establish the beneficial effectiveness of Mg as an adjunctive therapy in the critically ill patients suffering from sepsis or other systemic inflammatory conditions.