Effects of Thiopental on Endothelium-Dependent Relaxation in Porcine Coronary Arteries

Abstract

This study investigated the effects of thiopental on endothelium-dependent relaxation (EDR), and especially the effects on nitric oxide-and prostacyclin-independent EDR. Fresh porcine coronary artery rings (4 mm long), were consecutively tested with and without 20 μg/ml thiopental in Krebs–Henseleit solution. Indomethacin (10 μmol/1) was used in all experiments to eliminate prostacyclin effects. Prostaglandin F_2α (10 μmol/l) was used to induce contractions and bradykinin (10⁻¹⁰−10⁻⁵ M) was used to induce EDR. Experiments were also carried out using 300 μmol/1 N-nitro-l-arginine to block nitric oxide production and to assess the influence of thiopental on nitric oxide-and prostacyclin-independent EDR. Thiopental induced statistically significant increases in EDR at concentrations of 10⁻⁶−10⁻⁵ M bradykinin. Following nitric oxide production block, thiopental significantly reduced the relaxation response at concentrations of 10⁻⁸−10⁻⁵ M bradykinin. At a clinically relevant concentration of 20 μg/ml thiopental, a significant increase in EDR and a significant reduction in nitric oxide-and prostacyclin-independent relaxation was observed in porcine epicardial coronary arteries.