| Budget Amount *help |
¥2,300,000 (Direct Cost: ¥2,300,000)
Fiscal Year 1998: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1997: ¥1,700,000 (Direct Cost: ¥1,700,000)
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| Research Abstract |
Although the K-channel is a well-known regulator of the circulation in many organs such as heart and lung, little is known about the K-channel in cerebral microcirculation. We investigated the role of K-channel in regulation of cerebral microcirculation by meauring vessel diameter and the membrane potential simultaneously in isolated cerebral arterioles. (Methods) Penetrating intracerebral arterioles, about 50 mu m in diameter, were isolated surgically from the middle cerebral arteries of male Sprague-Dawley rats, and were cannulated under the inverted microscope. After transmural pressure was set to 60 mmHg and bath temperature was brought to 37.5ﾟC, the vessels developed spontaneous tone, contracting to approximately 70% of theri maximum passive diameters. The vessel diameter and the membrane potential of the smooth muscle cells were monitored simultaneously. The membrane potential was measured through the glass electrode filled with potassium acetate, which was penetrated into the cells using an electric pulse manipulator. (Results) When glibenclamide (10 mu M), an inhibitor of ATP-sensitive K-channels, was administered, the vessel diamter decreased by 5.1*4.4% from a diameter of 59.0*13.1 mu m (n= 10) and membrane potential was depolarozed form -33*4.2 mV to -29.7*3.6 mV.On the other hand, the membrane potential did not change at all when nitric oxide synthase inhibitor (NG-monomethyl-L-arginine : 100 mu M) was administered. (Conclusion) The present study suggests that K-channel plays an important role in maintenance of basic tone of arterioles in the cerebral microcirculation.
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