Vasopressin-Induced Protein Kinase C–Dependent Superoxide Generation Contributes to ATP-Sensitive Potassium Channel but Not Calcium-Sensitive Potassium Channel Function Impairment After Brain Injury

Pial artery dilation in response to activators of the ATP-sensitive K(+) (K(ATP)) and calcium-sensitive K(+) (K(Ca)) channels is impaired after fluid percussion brain injury (FPI). Vasopressin, when coadministered with the K(ATP) and K(Ca) channel agonists cromakalim and NS1619 in a concentration approximating that observed in cerebrospinal fluid (CSF) after FPI, blunted K(ATP) and K(Ca) channel-mediated vasodilation. Vasopressin also contributes to impaired K(ATP) and K(Ca) channel vasodilation after FPI. In addition, protein kinase C (PKC) activation generates superoxide anion (O(2)(-)), which in turn contributes to K(ATP) channel impairment after FPI. We tested whether vasopressin generates O(2)(-) in a protein kinase C (PKC)-dependent manner, which could link vasopressin release to impaired K(ATP) and K(Ca) channel-induced pial artery dilation after FPI.