Magnesium induced vascular relaxation and role of Calcium-dependent K+ Channels
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Date
2013-03
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Publisher
Janaki Medical College
Abstract
Background and objectives: Magnesium is established as a neuro-protective agent and now also known as a vasodilator. It has been known for treating vasospasm following subarachnoid hemorrhage. However, its action mechanism in cerebral vascular relaxation is not clear. Potassium channels play a pivotal role in the relaxation of smooth muscle cells. To investigate their role in magnesium-induced relaxation of basilar smooth muscle cells, we examined the effect of magnesium on potassium channels using the patch clamp technique on cells from rabbit basilar artery. Material and Methods: Fresh smooth muscle cells were isolated from the basilar artery by enzyme treatment. Whole cell current recording was done using patch-clamp technique. Appropriate bath solution was used to have potassium current. The effect of Magnesium was observed and to identify the potassium (K+) channel involved in the magnesium-induced currents, different potassium channel blockers were used. Results: Magnesium increased the step pulse-induced outward K+ currents by more than fortyfive percent over control level (p<0.01). The outward K+ current was decreased significantly by application of tetraethylammonium, a non-specific K+ channel blocker, and by iberiotoxin, a largeconductance Ca2+-activated K+ (BKCa) channel blocker, but was not inhibited by glibenclamide an ATP-sensitive K+ (KATP) channel blocker. Magnesium failed to increase the outward K+ currents in the presence of IBX. Conclusion: These results demonstrate that calcium dependent pottassium (BKCa) channels has role in magnesium induced vascular relaxation in rabbit basilar smooth muscle cells and needs to be worked out for human.
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Keywords
Electrophysiology, Magnesium, Patch Clamp, Vasoconstriction
Citation
Upadhyay-Dhungel K, Kim CJ, Dhungel A. Magnesium induced vascular relaxation and role of Calcium-dependent K+ Channels. Janaki Medical College Journal of Medical Science. 2013 Mar; 1(1): 9-13