Cardiovascular effects produced by systemic injections of nitro blue tetrazolium in the rat.

Nitro blue tetrazolium is a powerful electron acceptor which is widely used to localize NADPH-dependent flavin-containing enzymes known as NADPH diaphorases. By accepting electrons, nitro blue tetrazolium is known to inhibit the activity of these enzymes. The present study examined the effects of intravenous nitro blue tetrazolium on arterial blood pressure and regional blood flows in urethane-anesthetized rats. Nitro blue tetrazolium (0.1-5 mol/kg) produced a dose-dependent hypotension and differential effects on regional hemodynamics including decreases in hindquarter and mesenteric vascular resistances and a marked increase in renal resistance. These results demonstrate that systemic administration of nitro blue tetrazolium produces profound hemodynamic effects, the mechanisms of which remain to be elucidated.