Effect of triiodothyronine on postischemic myocardial function in the isolated heart.
Thyroid dysfunction has been shown to have a significant impact on hemodynamic status and cardiac function. The purpose of this study was to determine the influence of triiodothyronine (T3) on cardiac functional recovery after ischemia in a dose-dependent manner. Postischemic functional recovery was assessed in isolated rabbit hearts mounted in a modified Langendorff preparation. Left ventricular systolic, diastolic, and peak developed pressures were measured before and after ischemia, and calculated as a percentage of preischemic function. Two cohorts of hearts were studied: the first was exposed to warm ischemia until a myocardial contracture of 4 mmHg was produced; the second cohort was exposed to warm ischemia until a contracture of 15 mm Hg was observed. In each cohort, T3 was added to the perfusion solution after ischemia in a physiologic concentration (2.5 x 10(-9) g/mL; 1 x T3), as well as ten times (2.5 x 10(-8) g/mL; 10 x T3) and a hundred times (2.5 x 10(-7) g/mL; 100 x T3) the physiologic concentration. One group, given the carrier only but without T3, served as the control. Rabbit hearts exposed to a short period of ischemia (4-mmHg diastolic contracture) showed increased recovery with 1 x T3 and 10 x T3. 100 x T3 did not bring about improved left ventricular recovery versus that in the control group. Rabbit hearts in the 15 mm Hg-diastolic contracture cohort showed increased recovery with 10 x T3 but not with 1 x T3. 100 x T3 led to decreased recovery in this cohort versus that in the control group.(ABSTRACT TRUNCATED AT 250 WORDS)
Kadletz
M
M
Division of Cardiothoracic Surgery, Medical College of Virginia-Virginia Commonwealth University, Richmond.
Mullen
P G
PG
Ding
M
M
Wolfe
L G
LG
Wechsler
A S
AS
D000818:Animals; D003326:Coronary Circulation / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004489:Edema, Cardiac / Q000209:etiology; D006321:Heart / Q000187:drug effects* / Q000503:physiopathology; D066298:In Vitro Techniques; D009200:Myocardial Contraction / Q000187:drug effects; D017202:Myocardial Ischemia / Q000150:complications / Q000503:physiopathology*; D011817:Rabbits; D014284:Triiodothyronine / Q000008:administration & dosage / Q000494:pharmacology*; D016277:Ventricular Function, Left / Q000187:drug effects
D014284:Triiodothyronine