Regulation of Mg2+ efflux by cAMP in perfused rat heart and isolated ventricular myocytes |
Hyung-sub Kang, Jin-shang Kim, Chang-won Kang, Ho-il Lee |
Bio-Safety Research Institute, Chonbuk National University |
흰쥐의 심장과 심근세포에서 cyclic AMP에 의한 Mg2+ 유리조절 |
강형섭, 김진상, 강창원, 이호일 |
전북대학교 생체안전성연구소 |
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Abstract |
Although it has been reported that hormones or chemicals, which increase in intracellular cAMP, produced $Mg^{2+}$ release from the heart, it is not well characterized whether a specific $Mg^{2+}$ exchanger is involved in cAMP-induced $Mg^{2+}$ efflux in the mammalian hearts. In this work, we studied the relationship between the increase in intracellular cAMP and ion transport system on $Mg^{2+}$ regulation in the perfused rat heart and isolated myocytes. The $Mg^{2+}$ content in the perfusate and supernatant were measured by atomic absorption spectrophotometer. The addition of membrane permeable cAMP analogue to the perfused hearts and myocytes induced a $Mg^{2+}$ efflux in the dose dependent manners. $Mg^{2+}$ efflux was stimulated by cAMP modulators (forskolin, IBMX and Ro20-1724) in the perfused hearts and myocytes. cAMP-induced $Mg^{2+}$ efflux was inhibited by $H_7$, benzamil or imipramine in the perfused hearts and myocytes, but not by EIPA. We confirmed that a significant $Mg^{2+}$ efflux was induced by an increase in intracellular cAMP in the hearts and myocytes. The cAMP-induced increase of $Mg^{2+}$ efflux in the hearts may be involved in ion transport system ($Na^+-Ca^{2+}$ and $Na^+-Mg^{2+}$ exchanger). |
Key Words:
cAMP, $Na^+-Ca^{2+}$ exchange, $Na^+-Mg^{2+}$ exchange, heart |
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