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Biomedical subjects

J Kapitola

Publications and source records attributed to J Kapitola.

At least 73 records · Page 4Linked to original sources
PubMed1985

Thyroxine cardiomegaly in rats is not hypertension-bound.

For 13-27 days, male rats were given dried thyroid (Thyreoidin SPOFA) in their food, 0.9% NaCl to drink instead of water, or both. In all the experiments, Thyreoidin induced pronounced cardiomegaly. The blood pressure rose only after 0.9% NaCl combined with Thyreoidin and only in experiments lasting 13 or 16 days (not 25 and 27 days). After three weeks of the experiment, therefore, hypertension disappeared, but cardiomegaly persisted. In all the experimental groups, including the controls, a significant positive correlation was found between heart weight and adrenal weight, but not between heart weight and blood pressure or between adrenal weight and blood pressure. The adrenals may thus participate in some way in the development of thyroxine cardiomegaly.

Adrenal Glands↗
PubMed1981

Inhibition of the early circulatory effects of triiodothyronine in rats by propranolol.

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.

Animals↗