Protein kinase C delta modulates endothelial nitric oxide synthase after cardiac arrest.

We previously showed that inhibition of protein kinase C delta (PKC delta) improves brain perfusion 24 hours after asphyxial cardiac arrest (ACA) and confers neuroprotection in the cortex and CA1 region of the hippocampus 7 days after arrest. Therefore, in this study, we investigate the mechanism of action of PKC delta-mediated hypoperfusion after ACA in the rat by using the two-photon laser scanning microscopy (TPLSM) to observe cortical cerebral blood flow (CBF) and laser Doppler flowmetry (LDF) detecting regional CBF in the presence/absence of delta V1-1 (specific PKC delta inhibitor), nitric oxide synthase (NOS) substrate (L-arginine, L-arg) and inhibitor (N-omega-Nitro-L-arginine, NLA), and nitric oxide (NO) donor (sodium nitroprusside, SNP). There was an increase in regional LDF and local (TPLSM) CBF in the presence of delta V1-1 + L-arg, but only an increase in regional CBF under delta V1-1 + SNP treatments. Systemic blood nitrite levels were measured 15 minutes and 24 hours after ACA. Nitrite levels were enhanced by pretreatment with delta V1-1 30 minutes before ACA possibly attributable to enhanced endothelial NOS protein levels. Our results suggest that PKC delta can modulate NO machinery in cerebral vasculature. Protein kinase C delta can depress endothelial NOS blunting CBF resulting in hypoperfusion, but can be reversed with delta V1-1 improving brain perfusion, thus providing subsequent neuroprotection after ACA.