alpha(1)-Agonists-induced Mg(2+) efflux is related to MAP kinase activation in the heart.
The stimulation of the alpha(1)-adrenergic receptor with phenylephrine results in the significant extrusion of Mg(2+) from the rat heart and cardiomyocytes. Phenylephrine-induced Mg(2+) extrusion is prevented by the removal of extracellular Ca(2+) or by the presence of Ca(2+)-channel blockers such as verapamil, nifedipine, or (+)BAY-K8644. Mg(2+) extrusion is almost completely inhibited by PD98059 (a MAP kinase inhibitor). The simultaneous addition of 5mM Ca(2+) and phenylephrine increases the extrusion of Mg(2+) from perfused hearts and cardiomyocytes. This Mg(2+) extrusion is inhibited by more than 90% when the hearts are preincubated with PD98059. ERKs are activated by perfusion with either phenylephrine or 5mM Ca(2+). This ERK activation is inhibited by PD98059. Overall, these results suggest that stimulating the cardiac alpha(1)-adrenergic receptor by phenylephrine causes the extrusion of Mg(2+) via the Ca(2+)-activated, Na(+)-dependent transport pathway, and the ERKs assists in Mg(2+) transport in the heart.
College of Veterinary Medicine, Chonbuk National University, Jeonju 561-756, Republic of Korea.
Shang-Jin
SJ
Kim
Hyung-Sub
HS
Kang
Myung-Suk
MS
Kang
Xianfeng
X
Yu
Sang-Yeol
SY
Park
In-Shik
IS
Kim
Nam-Soo
NS
Kim
Sung-Zoo
SZ
Kim
Yong-Geun
YG
Kwak
Jin-Shang
JS
Kim
D058646:Adrenergic alpha-1 Receptor Agonists; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured; D004789:Enzyme Activation; D020935:MAP Kinase Signaling System / Q000502:physiology*; D008274:Magnesium / Q000378:metabolism*; D008297:Male; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D032383:Myocytes, Cardiac / Q000378:metabolism*; D010656:Phenylephrine / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D018340:Receptors, Adrenergic, alpha-1 / Q000378:metabolism*
D058646:Adrenergic alpha-1 Receptor Agonists; D018340:Receptors, Adrenergic, alpha-1; D010656:Phenylephrine; D020928:Mitogen-Activated Protein Kinases; D008274:Magnesium; D002118:Calcium