Assuntos
Angiotensina II/farmacologia , Antitireóideos/farmacologia , Isoproterenol/farmacologia , Radioisótopos/metabolismo , Hormônios Tireóideos/farmacologia , Animais , Antipirina/metabolismo , Radioisótopos do Iodo/metabolismo , Masculino , Microesferas , Ratos , Rubídio/metabolismo , Radioisótopos de Estrôncio/metabolismoRESUMO
Using the 133Xe tissue clearance method, the blood flow in the greater trochanter of the femur was studied in 30 patients with acromegaly. Both the washout rate constant (k2) and blood flow (P2) values are significantly decreased in acromegaly (p less than 0.01). There is a significant negative correlation (r = -0.42, p less than 0.05) between the flow values and mean daily concentrations of growth hormone in serum of acromegalic patients. The observations is presented as a preliminary evidence of a possible influence of growth hormone on the blood flow in bone.
Assuntos
Acromegalia/fisiopatologia , Osso e Ossos/irrigação sanguínea , Adulto , Osso e Ossos/metabolismo , Feminino , Fêmur/irrigação sanguínea , Humanos , Masculino , Pessoa de Meia-Idade , Fluxo Sanguíneo Regional , Radioisótopos de Xenônio/metabolismoAssuntos
Hemodinâmica/efeitos dos fármacos , Teofilina/farmacologia , Tireoide (USP)/farmacologia , Hormônios Tireóideos/farmacologia , Tri-Iodotironina/farmacologia , Animais , Pressão Sanguínea/efeitos dos fármacos , Débito Cardíaco/efeitos dos fármacos , Frequência Cardíaca/efeitos dos fármacos , Ratos , Volume Sistólico/efeitos dos fármacos , Resistência Vascular/efeitos dos fármacosRESUMO
In two identical experiments, A and B, we studied the effect of the simultaneous l.v. injection of propranolol (Inderal, 0.5 mg/kg) on the circulatory effects of triiodothyronine (T3 500 microgram/kg i.v. 3 hours before measuring). The two substances act at different rates and so the blocking effect of propranolol preceded the development of the circulatory effects of T3. Cardiac output was measured by the Evans blue dilution method, the heart rate was calculated from the ECG recording and blood pressure was measured with a mercury manometer; stroke volume and total peripheral vascular resistance were also calculated. The isolated injection of T3 was followed by a significant increase in cardiac output (experiment A: 129%, B: 118%) and stroke volume (A: 125%, B: 118%) and by a drop in total peripheral vascular resistance (A: 82%, B: 85%). There was no change, in this early phase, in the heart rate or blood pressure. No changes were found 3 hours after the isolated administration of Inderal (the maximum effect of propranolol is attained in 30-60 min). During the same period, the above initial effects of T3 were completely suppressed by the simultaneous injection of Inderal. These results were probably related to the experimental conditions (early and not very marked changes after T3), but they demonstrate that the initial effects of T3 on cardiac performance and on the peripheral blood vessels can be completely suppressed by a block of beta receptors. From this it can be concluded that beta-adrenergic regulation is an important part of the mechanism of the early haemodynamic action of T3.
