Direct effects of triiodothyronine on human internal mammary artery and saphenous veins

• Published in: Journal of cardiothoracic and vascular anesthesia 1997-06, Vol.11 (4), p.463-466
• Main Authors: Jill Krasner, L., Wendling, Woodrow W., Cooper, Suzane C., Chen, Dong, Hellmann, Steven K., Eldridge, Charles J., McClurken, James B., Jeevanandam, Valluvan, Carlsson, Christer
• Format: Article
• Language: English
• Subjects: Biological and medical sciences; Blood Pressure - drug effects; Cardiotonic agents; Cardiotonic Agents - administration & dosage; Cardiotonic Agents - pharmacology; Cardiovascular system; Central Venous Pressure - drug effects; Coronary Artery Bypass; Dose-Response Relationship, Drug; human; Humans; Isometric Contraction - drug effects; Isotonic Solutions; mammary arteries; Mammary Arteries - drug effects; Medical sciences; Muscle, Smooth, Vascular - drug effects; Pharmacology. Drug treatments; Phenylephrine - pharmacology; Potassium - pharmacology; Propranolol - pharmacology; Prospective Studies; saphenous vein; Saphenous Vein - drug effects; triiodothyronine; Triiodothyronine - administration & dosage; Triiodothyronine - pharmacology; vascular smooth muscle; Vasoconstriction - drug effects; Vasoconstrictor Agents - pharmacology; Vasodilation; Vasodilator Agents - administration & dosage; Vasodilator Agents - pharmacology; Vasomotor System - drug effects
• ISSN: 1053-0770; 1532-8422
• DOI: 10.1016/S1053-0770(97)90056-2

Objective: Thyroid hormone (3,5,3′-triiodo-L-thyronine) is under investigation as a positive inotrope and vasodilator for patients undergoing cardiac surgery. This study determined the direct effects of triiodothyronine on human blood vessels. Design: Prospective, controlled, in vitro study. Setting: Laboratory facility in a university teaching hospital. Participants: Small excess segments of internal mammary arteries or saphenous veins were obtained from patients undergoing coronary artery bypass surgery. Interventions: Vessel segments were cut into rings to measure isometric tension development in isolated tissue baths containing Krebs-Ringer bicarbonate solution at 37°C. Rings were prestretched in vitro to resting tensions analogous to mean arterial or central venous pressures in vivo and then constricted with potassium or phenylephrine. Rings were exposed to increasing concentrations of triiodothyronine (4 × 10 −12to 1 × 10 −4 mol/L) to obtain dose-response curves. Measurements and Main Results: High concentrations (≥3.3 × 10 −5 mol/L) of triiodothyronine produced dose-dependent relaxation of preconstricted rings. The relaxation was not selective for arteries or veins at arterial resting tensions, and with either potassium or phenylephrine as a vasoconstrictor. Propranolol had little effect on subsequent triiodothyronineinduced relaxation of potassium-constricted rings at resting arterial tensions. Conclusions: Triiodothyronine, in supraphysiological and suprapharmacological concentrations, dilates preconstricted rings of human blood vessels in vitro; however, triiodothyronine had no demonstrable vasomotor effects on human internal mammary artery or saphenous vein in clinically relevant concentrations (10 −9 to 10 −8 mol/L). Triiodothyronine administration in vivo most likely has little direct effect on the tone of human vascular smooth muscle, particularly coronary artery bypass conduits.