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KMID : 0811719980020010049
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Korean Journal of Physiology & Pharmacology
1998 Volume.2 No. 1 p.49 ~ p.54
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Effects of Histamine H2-Receptor Stimulation on Mg2＋ Efflux in Perused Guinea Pig Heart
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Hyung-Sub Kang
Sung-Eun Change/Chang-Won Kang/Soo-Wan Chae/Jin-Sang Kim
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Abstract
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Mg2+ is an important regulator of many cardiac functions. However, regulation of intracellular Mg2+ activity in the heart is not well characterized. To assess the effect of histamine H2-receptor stimulation on intracellular Mg2+ regulation, changes in extracellular Mg2+ concentration were examined under a variety of conditions in perfused guinea pig hearts. Mg2+ in the cardiac perfusate was measured by atomic absorbance spectrophotometry. The histamine (10?6 M) inuced a marked Mg2+ efflux from the heart. The H2-receptor antagonists, cimetidine (10?6 M), ranitidined (10?5 M), but not a H1-receptor antagonist, diphenhydramine (3×10?6 M), completely blocked the histamine-induced Mg2+ efflux. The Mg2+ efflux could also be induced by forskolin (3×10?6 M), 8-Cl-cAMP (2×10?4 M), permeable cAMP analogue, or dimaprit, (10?5 M). However, the carbachol (10?5 M) considerably decreased the efflux of Mg2+. In the presence of papaverine (10?5 M), a phosphodiesterase inhibitor, dimaprit-induced Mg2+ efflux was potentiated. These results suggest that a significant Mg2+ efflux from perfused guinea pig heart by histamine can be induced by the histamine H2-receptor stimulation and it is suggested that cytosolic cAMP may be linked.
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KEYWORD
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Histamine, Magnesium, Dimaprit, cAMP, Heart, Guinea pig,
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