Dopamine D1 and D5 receptors differentially regulate oxidative stress through paraoxonase 2 in kidney cells.

BACKGROUND: The renal dopaminergic system plays an important role in the pathogenesis of hypertension. Dopamine D1-like receptors (D1R and D5R) decrease reactive oxygen species (ROS) production via inhibition of pro-oxidant enzymes such as NADPH oxidase. Paraoxonase 2 (PON2) is also involved in the inhibition of NADPH oxidase activity. Therefore, we tested the hypothesis that D1R and D5R inhibit ROS production by increasing the expression of PON2, including those in membrane microdomains. METHODS AND RESULTS: PON2 colocalized with D1R and D5R in mouse renal proximal tubules (RPTs), human RPT (hRPT) cells, and HEK293 cells heterologously expressing human D1R (HEK-hD1R) or D5R (HEK-hD5R). Fenoldopam, an agonist for both D1R and D5R, increased PON2 co-immunoprecipitation with D1R and D5R in HEK-hD1R and HEK-hD5R cells, respectively. Silencing PON2 increased ROS production and NADPH oxidase activity, and impaired the inhibitory effect of fenoldopam. Fenoldopam increased PON2 protein in both lipid rafts (LRs) and non-LRs in HEK-hD1R cells, but only in non-LRs in HEK-hD5R and hRPT cells. Long-term (hrs) fenoldopam stimulation increased PON2 protein in a time-dependent manner in HEK-hD5R, but not in HEK-hD1R cells. Because the effects of fenoldopam on non-LR and total PON2 expressions were similar in HEK-hD5R and hRPT cells, additional studies were performed to determine the relationship between D5R and PON2. Renal PON2 protein was decreased in D5(-/-) mice. In hRPT cells, silencing D5R decreased PON2 expression and increased ROS production. CONCLUSIONS: We conclude that D1-like receptors inhibit ROS production by altering PON2 distribution in membrane microdomains in the short-term, and by increasing PON2 expression in the long-term.

Consensus perspectives on surgery in haemophilia patients with inhibitors: summary statement.

Summary. Participants in an international workshop on surgery in haemophilia patients with inhibitors developed a consensus summary of the findings and conclusions of the meeting. In the consensus, participants agreed upon revised definitions for minor and major surgery, including an intermediate degree of surgery. An evaluation system of intraoperative and postoperative bleeding was developed. Recommended doses of FEIBA((R)) and rFVIIa (both in bolus injections and in continuous infusion) for surgery were agreed. Participants also agreed on the main blood tests to be performed peri-operatively. They also suggested the need of a prospective evaluation in the future. Finally, the approximate number of surgical procedures and costs performed on haemophilia patients with inhibitors were analysed.