Repository of Research and Investigative Information

Repository of Research and Investigative Information

Hormozgan University of Medical Sciences

Mg2+-induced adenosine-receptor mediated relaxations in mesenteric vascular beds of diabetic rats

(2012) Mg2+-induced adenosine-receptor mediated relaxations in mesenteric vascular beds of diabetic rats. General Physiology and Biophysics.

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Abstract

Abstract Our previous studies showed that the magnesium Mg2+-induced relaxations were completely dependent on concentration of nitric oxide (NO) in non-diabetic rat mesenteric vascular beds, in diabetic rats other mechanisms may be involved. The present study was designed to determine the role of adenosine receptor in Mg2+-induced relaxation in streptozotocin (STZ)-induced diabetic rats vessels. Diabetes was induced by the intravenous injection of 60 mg/kg STZ. Eight weeks after diabetes induction, superior mesenteric arteries were isolated and perfused according to the McGregor method. Prepared vascular beds were constricted with phenylephrine to induce 70-75% of maximal constriction (0.001 M). Mg2+ at concentrations of 10(-4) to 10(-1) M were added into the medium and perfusion pressure was recorded. Theophylline (1 mM), and 3,7- dimethyl-1- propargylxanthine (0.01 mu M) were added into medium 20 min before phenylephrine administration. In the presence of theophylline, vasorelaxation induced by high dose of Mg2+ (from 0.03 to 0.1 M) was totally suppressed. In presence of N(omega)-nitro-L-arginine methyl ester (L-NAME), the response of Mg2+ was completely inhibited at low dose of Mg2+. But, Mg2+-induced relaxation in the presence of adenosine A2a receptor blocker was significantly suppressed in high dose of Mg2+. Mg2+-induced relaxation in the presence of an A2a receptor blocker was not suppressed either by denudation of endothelium or presence of L-NAME. From the results of this study it may be concluded that Mg2+-induced relaxation at high concentrations is mediated by adenosine A2a receptors, but at low concentrations Mg2+-induced relaxation is dependent on NO.

Item Type: Article
Keywords: Diabetes; Magnesium; Adenosine A2a receptor; Nitric oxide; Mesenteric bed ENDOTHELIUM-DEPENDENT RELAXATION; ORAL MAGNESIUM; BLOOD-VESSELS; RESPONSIVENESS; PHARMACOLOGY; STIMULATION; RESPONSES; TONE
Subjects: QU Biochemistry. Cell Biology and Genetics > QU 300-560 Cell Biology and Genetics
Depositing User: مهندس هدی فهیم پور
URI: http://eprints.hums.ac.ir/id/eprint/5210

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