Potassium dilates rat cerebral arteries by two independent mechanisms

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Abstract
Cerebral blood flow is regulated by brain metabolism, and there is evidence to suggest that changes in extracellular potassium concentration are important in linking brain metabolic activity with blood supply. In this study, the effect of low concentrations of potassium on the spontaneous tone of resistance-sized isolated posterior cerebral arteries from Wistar-Kyoto rats was examined. At a transmural pressure of .apprx.58 mmHg, the vessels developed spontaneous tone that was 69 .+-. 2% of their fully relaxed diameter of 184 .+-. 2 .mu.m (n = 50). Introduction of potassium (7 mM K+) results from activation of a ouabain-, barium-, and cesium-sensitive process. The latter process describes a means by which potassium may effect prolonged changes in cerebral blood flow.

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