Triiodothyronine Acutely Increases Blood Flow in the Ventricles and Kidneys of Anesthesized Rabbits

Abstract

Thyroid hormone (triiodothyronine [T(3)]) has various nongenomic effects, including alterations in glucose and fatty acid metabolism, augmentation of intracellular Ca(2+), enhancement of myocardial contractility, and vascular dilatation. However, its effect on regional blood flow remains to be established. We have measured the effect of T(3) on blood flow in major organs of anesthetized rabbits in vivo using the microsphere method. Under artificial respiration, nonradioactive microspheres (5 x 10(5)) labeled with barium were injected to measure blood flow at control level. Then, T(3) (50 microg/kg per milliliter) was administered and microspheres labeled with iodine (5 x 10(5)) were injected. The atria, ventricles, kidneys, and right upper limb were excised and their contents of microspheres were evaluated. Blood flow in the ventricles was significantly increased by T(3) (2.9 +/- 0.3 versus 3.4 +/- 0.3 mL/min per gram, vehicle versus T(3)). Similarly, blood flow in the kidneys was significantly higher after T(3) injection (4.3 +/- 0.5 versus 5.1 +/- 0.5 mL/min per, vehicle versus T(3)). The blood flow in the atria and skeletal muscles remained unchanged. These results indicate that the vasodilatory response to T(3) is not uniform and occurs preferentially in major organs such as cardiac ventricles and kidneys; this may be relevant to the T(3)-induced improvement of cardiac function.

The role of thyroid hormone in the pathophysiology of heart failure: clinical evidence

“…Administration of T3 in vivo in the circulation of major organs of anesthetized rabbits is associated with a vasodilatory response that occurs preferentially in the ventricles and kidneys, but not in the atria or skeletal muscle [44]. The observation of a vasodilatory response induced by TH in coronary arteries is in line with previous reports by Yoneda et al that showed that a bolus injection of T3 or T4 in rat coronary arteries elicited a transient, dose-dependent decrease in coronary perfusion pressure, as well as an increase in arterial vasodilation [45].…”

Low Triiodothyronine Syndrome Increased the Incidence of Acute Kidney Injury After Cardiac Surgery

“… 23 An animal study also showed that thyroid hormones (eg, T3) can increase in blood flow in the ventricles and kidneys, a possible mechanism that underlies T3-induced improvement of cardiac and renal function. 24 Kumar et al have revealed that the patients who received levothyroxine experienced rapid improvement in hemodynamics. 25 In addition, histologic studies have documented the effects of T3 on outer and cortical medullary tubular segments, especially the distal convoluted tubules and proximal tubules.…”