The development of heart lesions induced by isoprenaline (ISO) was quantitatively evaluated by 203Hg-Mercurascan (MSC) which was taken up and retained in the damaged cells. After the administration of ISO, the MSC uptake increased immediately at a constant rate, which was independent of the dose of ISO. A higher cardiotoxic effect of increased doses of ISO was caused by prolongation of the time during which the development of heart lesions proceeded. Later, when the damaged cells were subjected to cytolysis, MSC uptake decreased. The blockade of the effect of ISO by methypranol immediately stopped any further increase of MSC uptake. The accumulation of other labelled substances (Neohydrin, HgCl2, CaCl2) in the damaged myocardium was compared with the uptake of MSC. MSC and HgCl2 in particular are suitable for the observation of early changes; relatively less CaCl2 accumulated in the damaged hearts, but it can be used for the detection of more advanced lesions.

• MeSH
• isoprenalin * MeSH
• kardiomyopatie chemicky indukované   patologie   MeSH
• krysa rodu Rattus MeSH
• myokard patologie   MeSH
• radioizotopy rtuti MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• isoprenalin * MeSH
• radioizotopy rtuti MeSH

The influence of spontaneous motor activity on the development of isoprenaline-induced heart lesions was studied in male rats of different ages. The extent of the lesions was evaluated quantitatively from raised accumulation of 203HgCl2 in the damaged tissue. Spontaneous activity in rotation cages rose with the animals, age and attained maximum values (6 562 m/d) at 3 months. The increase in motor activity in 10 months was very low and attained only 561 m/d. In all the experimental groups in which spontaneous activity was higher than this limit, a decrease in the cardiotoxic effect of isoprenaline was found after 2--3 weeks. The extent of the heart lesions in the individual animals was not proportional to the degree of their motor activity. The smallest myocardial damage was not found in animals which ran the most metres and vice versa. A marked decrease in the extent of the heart lesions occurred when the motor regimen was prolonged to 70 days. After a three days' break in the motor regimen, reduction of the cardiotoxic effect was still maintained. The extent of the heart lesions after 14 days' interruption corresponded to the values found in animals which were not allowed increased motor activity.

• MeSH
• časové faktory MeSH
• inbrední kmeny potkanů MeSH
• isoprenalin MeSH
• krysa rodu Rattus MeSH
• nemoci srdce chemicky indukované   MeSH
• pohybová aktivita fyziologie   MeSH
• stárnutí MeSH
• tělesná hmotnost MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• isoprenalin MeSH

The authors studed the effect of pregnancy and lactation on the resistance of myocardium against damage. Lesions of the heart were induced by isoprenaline in vivo. The extent of lesions was evaluated macroscopically and quantitatively according to the increased accumulation of 203HCl2 in the damaged heart tissue. In vitro, the damage of the isolated right ventricle was induced by anoxia and the resistance of heart tissue was evaluated according to the recovery of contractility. During the first week after delivery, the extent of isoprenaline-induced heart lesions was increased in nursing mothers as compared with virgin females of the same age. The mortality did not change significantly. Restitution of contractility of the right ventricle in vitro and anoxia was lower than in virgin females. In nursing mothers 35 days after delivery, the mortality and the extent of heart lesions induced by isoprenaline was significantly reduced as compared with virgin females. Furthermore, the resistance to anoxia of their isolated right ventricle was higher than that of virgin females. The reduced effect of isoprenaline lasted for several months after devlivery. The mortality and the extent of isoprenaline-induced heart lesions were not reduced significantly 35 days after delivery in non-lactating mothers, which were deprived of their young.

• MeSH
• hypoxie patofyziologie   MeSH
• isoprenalin MeSH
• kardiomyopatie chemicky indukované   MeSH
• kardiovaskulární komplikace v těhotenství chemicky indukované   patofyziologie   MeSH
• kontrakce myokardu MeSH
• krysa rodu Rattus MeSH
• laktace * MeSH
• techniky in vitro MeSH
• těhotenství MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• těhotenství MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• isoprenalin MeSH

The conditions under which increased motor activity leads to raised resistance of the myocardium to injury were studied. Motor activity was raised by running on a treadmill; myocardial resistance was evaluated quantitatively from the extent of isoprenaline (ISO)-induced lesions. After 3 weeks of forced running (5 days a week), using an adequate daily dose, the cardiotoxic effect of ISO was reduced. Adequacy of the daily dose of exercise depended both on the distance run per day and on the rate at which the animals ran. If the training regimen was continued for further weeks, with the same daily dose of exercise, there was no significant increase in protection of the myocardium. In animals aged less than 3 months, myocardial resistance changed after higher daily doses of running than those needed in older animals. The cardioprotective effect of increased motor activity was not conditioned by increase in the weight of the myocardium.

• MeSH
• inbrední kmeny potkanů MeSH
• isoprenalin toxicita   MeSH
• krysa rodu Rattus MeSH
• pohybová aktivita * MeSH
• poranění srdce chemicky indukované   prevence a kontrola   MeSH
• tělesná námaha MeSH
• věkové faktory MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• isoprenalin MeSH