Endothelial cationic amino acid transporter-1 overexpression blunts the effects of oxidative stress on pressor responses to behavioural stress in mice

Observational studies indicate that psychological stress may contribute to the pathogenesis of hypertension and this may be further accentuated by factors such as endothelial dysfunction. On this basis, we aimed to determine whether oxidative stress enhances pressor responses to stressful stimuli and whether augmenting endothelial function by, increasing the transport of L-arginine, can counter the effects of oxidative stress. Telemetry probes were used to measure mean arterial pressure (MAP) in wild type (WT; n=6) and endothelial CAT1 overexpressing mice (n=6) before and during an aversive (restraint) and a non-aversive (almond feeding) stressor. The superoxide dismutase inhibitor, diethyldithiocarbamic acid (DETCA; 30 mg/kg/day; 14 days) was then administered via a minipump to induce oxidative stress. Stress responses to feeding and restraint were repeated during the 11-12th day of DETCA infusion. In WT mice, pressor responses to restraint and feeding were augmented during infusion of DETCA (35 +/- 1 and 28 +/- 1 mmHg, respectively) compared to respective pre-treatment responses (28 +/- 2 and 24 +/- 1 mmHg, respectively; P