非甲状腺疾患における甲状腺ホルモン代謝異常に関する研究:第1編実験的心筋梗塞犬における血中甲状腺ホルモン動態と血行動態諸量の検討
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To assess the changes in thyroid hormone metabolism after the onset of acute myocardial infraction (AMI), serum T<SUB>4</SUB> and T<SUB>3</SUB> levels were serially measured for 24 hours after the coronary artery ligation in dogs. The effect of thyroid hormone administration on hemodynamics in these dogs were also studied to clarify the possible usefulness of thyroid hormone therapy in nonthyroidal illness (NTI). Dogs were anesthetized with ketamine using "Micro-Mini" drip administration. Coronary artery ligation was performed in 8 dogs (MI group) Open chest operation was performed in 8 dogs, but their coronary arteries were not ligated and were used as control (cont. group). Blood samples were drawn before and 1, 3, 6, 12, 18 and 24 hours after coronary artery ligation, and serum levels of T<SUB>4</SUB> and T<SUB>3</SUB> were measured using the TDX T<SUB>4</SUB> system and a commercial RIA kit, respectively. Various hemodynamic parameters (heart rate, mean blood pressure, max dp/dt, left ventricular end-diastolic pressure, cardiac output) were measured at the same time mentioned above.<BR>All the hemodynamic parameters remained within normal range for 24 hours in the control group. Serum T<SUB>4</SUB> and T<SUB>3</SUB> levels, however, showed slight, but significant decreases due to general anesthesia and open chest operation in the control group. On the other hand, hemodynamic parameters were maintained in the normal ranges only for 12 hours, and gradually deteriorated in the MI group. Moreover, it was remarkable that both T<SUB>4</SUB> and T<SUB>3</SUB> levels were decreased immediately after the ligation in this group, T<SUB>4</SUB> being less than 0.1μg/ dl and T<SUB>3</SUB> less than 10ng/dl. They continued to show the low values thereafter. When T4<SUB>4</SUB> (30μg/24 hours), and T<SUB>3</SUB> (7, 14 or 21 μg/24 hours) were continuously infused intravenously for 24 hours after the coronary artery ligation in 10 dogs, serum T4 levels were maintained in the normal range of the dog (1.5 -3.6μg/dl) and the serum T<SUB>3</SUB> levels were increased to the low normal range. However, there were no significant differences in hemodynamic indices between the thyroid hormone treated groups and the non-treated group.<BR>These data show that T<SUB>4</SUB> and T<SUB>3</SUB> concentrations decrease prior to the deterioration of cardiac function. Moreover, the present findings also suggest that administration of thyroid hormone has no benefit in patients with NTI associated with low T<SUB>4</SUB> and T<SUB>3</SUB> levels.
- 一般社団法人 日本内分泌学会の論文