DIFFERENTIAL REGULATION OF CIRCULATING MG2+ IN THE RAT BY BETA(1)-ADRENERGIC AND BETA(2)-ADRENERGIC RECEPTOR STIMULATION

被引:40
作者
KEENAN, D
ROMANI, A
SCARPA, A
机构
[1] CASE WESTERN RESERVE UNIV,SCH MED,DEPT PHYSIOL & BIOPHYS,CLEVELAND,OH 44106
[2] CASE WESTERN RESERVE UNIV,SCH MED,DEPT SURG,CLEVELAND,OH 44106
关键词
MG2+; CIRCULATION; BETA-ADRENERGIC STIMULATION; RATS;
D O I
10.1161/01.RES.77.5.973
中图分类号
R5 [内科学];
学科分类号
1002 ; 100201 ;
摘要
Extracellular Mg2+ homeostasis was studied in vivo in the anesthetized rat. Animals were infused with isoproterenol (ISO) for 10 minutes, and serum Mg2+ was measured after the infusion and then 10 and 20 minutes later. A dose-dependent increase in circulating Mg2+ was observed in animals infused with ISO at a rate of 0.1 mu g . kg(-1). min(-1) or higher. The time course of the effect demonstrated that circulating Mg2+ continued to increase 20 minutes after the end of the ISO infusion. A predicted maximal increase in serum Mg2+ concentration of 19.3% was derived with a predicted EC(50) of 0.08 mu g . kg(-1). min(-1). The maximal percent increase corresponded to a net increase of 6.7 mu mol/300 g body wt. Because infusion of ISO resulted in changes in hemodynamic parameters, most notably a drop in blood pressure, a group of animals was infused with nitroprusside to mimic the hypotensive response via a nonadrenergic mechanism. Under these conditions, there was a transient increase in circulating Mg2+ that was largely inhibited by propranolol, indicating that hypotension per se was not responsible for the mobilization of Mg2+. Infusion of salbutamol, but not prenalterol, also induced an increase in circulating Mg2+. Pretreatment with butoxamine, ICI-118551, or propranolol prevented the ISO-induced increase in serum Mg2+. Pretreatment with atenolol minimally affected the ISO-induced changes in circulating Mg2+. Pretreatment with CGP-20271A actually enhanced the ISO-induced increase in circulating Mg2+. This evidence demonstrates the existence of a pool of Mg2+ that is mobilized into the circulation in response to selective beta(2)-adrenergic stimulation.
引用
收藏
页码:973 / 983
页数:11
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