Neuronal NO mediates cerebral vasodilator responses to K in hypertensive rats

Abstract

Potassium ion (K+) normally causes cerebral vasodilatation by activating inwardly rectifying K+ (KIR) channels. We tested whether chronic hypertension affects the magnitude and/or mechanism of K+-induced cerebral vasodilatation in vivo. Basilar artery responses were examined in anesthetized Wistar-Kyoto (WKY; mean arterial pressure, 114±4 mm Hg) and spontaneously hypertensive (SHR; 176±3 mm Hg) rats. In WKY, elevating cerebrospinal fluid K+ concentration from 3 mmol/L to 5 and 10 mmol/L caused vasodilatation (percent maximum, 12±1 and 48±7, respectively). The response to 5 mmol/L K+ was greater in SHR (percent maximum, 17±2 [P<0.05 versus WKY] and 49±4). The KIR channel inhibitor, barium ion..