Differential responses of regional vascular beds to local injection of agmatine in rats.
In 66 anaesthetized rats, the effects of local injection of agmatine on femoral, renal, and mesenteric vascular beds were investigated respectively by constant flow perfusion method. The results are as follows. (1) Agmatine (0.1, 0.5, 1 mg/kg) increased the perfusion pressure (PP) of femoral vascular bed in a dose  dependent manner. The effect of agmatine (1 mg/kg) was completely blocked by pretreatment with idazoxan (0.5 mg/kg), an antagonist for imidazoline receptors (IR) and alpha(2)-adrenergic receptors (alpha(2)-AR), and yohimbine (1 mg/kg), a selective alpha(2)-AR antagonist. (2) Agmatine also increased the PP of renal vascular bed in a dose-dependent manner, and agmatine at high dose (1 mg/kg) caused a biphasic increase of PP in renal vascular bed. Idazoxan blocked these effects completely, while yohimbine led the agmatine  induced effect to a decrease in the PP of renal vascular bed. (3) Agmatine decreased the PP of mesenteric vascular bed in a dose-dependent manner, an effect which was completely blocked by idazoxan, but unaffected by yohimbine. From the results obtained, it is concluded that agmatine differentially affects the vascular tone in the femoral, renal, and mesenteric vascular beds.
Li
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Department of Physiology, Institute of Basic Medicine, Hebei Medical University, Shijiazhuang 050017, China.
Fan
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Wang
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He
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D000376:Agmatine / Q000494:pharmacology*; D000818:Animals; D004305:Dose-Response Relationship, Drug; D006614:Hindlimb / Q000098:blood supply; D007668:Kidney / Q000098:blood supply*; D008297:Male; D008643:Mesentery / Q000098:blood supply*; D010477:Perfusion; D051381:Rats; D017207:Rats, Sprague-Dawley; D014661:Vasoconstriction / Q000187:drug effects; D014664:Vasodilation / Q000187:drug effects
D000376:Agmatine