Prevention of experimental calcinosis by salmon calcitonin in rats.

The effects of salmon calcitonin on calcium overload and its deposition in the rat aorta was studied. Calcitonin administered 4 days to rats i.p. in doses of 10 IU/kg body weight blocked the development of calcinosis induced by a single dose of vitamin D3 (300,000 IU/kg body weight, orally). This was demonstrated biochemically, histochemically and by electron microscopic methods.

[Present methods of inducing calcinosis and atherosclerosis and perspectives of pharmacologic prevention]. / Súcasné metódy vyvolania kalcinózy a aterosklerózy a perspektíva farmakologickej prevencie.

In the light potential preventive pharmacotherapy of experimental atherosclerosis, attention has been focused on the effect of some substances tested in models that may represent human atherosclerosis. Calcium antagonists of various chemical groups administered simultaneously prevent the accumulation of calcium in cells under conditions of experimental calcinosis and atherosclerosis, as e.g. in spontaneously hypertensive rats, in rabbits on cholesterol diet, at administration of high doses of vitamin D, and on using the cuff technique. The results indicate that substances involved in the metabolism of calcium affect basic pathogenic processes of calcinosis and atherosclerosis.

Bayliss myogenic response in the isolated ductus arteriosus of guinea-pig and rabbit fetuses.

Isolated ductus arteriosus responds by marked constriction to increases in perfusion pressure. If, however, these increases exceed 90 mm Hg-130 mm Hg, the vessel suddenly dilates and its responsiveness becomes depressed. The importance of these findings in postnatal closure of ductus arteriosus is discussed.

Effect of reserpine on the calcium content of rat aorta at different stages of development.

The preadministration of reserpine (2.5 mg/kg b.w. per os) 24 hours before the experiment did not statistically significantly affect the calcium content of the aorta of 21- and 42-day-old rats. In 90-day-old and older rats it produced a statistically significant decrease in the calcium content of the thoracic segment of the aorta, however.

[Occlusion of the ductus arteriosus in the rabbit. A light and electron microscopic study]. / Der Verschluss des Ductus arteriosus des Kaninchens--Eine licht- und elektronenmikroskopische Studie

The development of changes appearing with the closure of ductus arteriosus was followed in mature rabbit foetuses with the help of light and electron microscopy. In the foetuses, in which there was no spontaneous respiration of atmospheric air before fixation the ductus remained opened. In smooth muscle cells of the media there were enlarged cisternae of the endoplasmic reticulum being partially decayed. The foetuses that respired for about one minute had the ductus contracted to various degree and the endothelial cells were expelled into the lumen. In the foetuses respiring for 10 minutes the ductus were more contracted. The endothelium was considerably waved and the agglomeration of smooth muscle cells appeared. In the endothelial and musclar cells the endoplasmic reticulum was richer, and in a lot of places considerably disturbed. The ductus of foetuses respiring for 15 minutes had the lumen completely closed. The smooth muscle cells had a significantly changed their internal structure. The possibility of the direct transformation of the endoplasmic reticulum of the smooth muscular cells into inclusion bodies during the ductus arteriosus closure is discussed.