ISSN:
1432-2307
Keywords:
Catecholamine
;
Angiotensin
;
Ouabain
;
Dihydrotachysterol
;
Rat heart
;
Myocardial necrosis
;
Electrolyte concentration
;
Electron microscopy
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Description / Table of Contents:
Zusammenfassung Noradrenalin und Angiotensin in hohen Dosen allein oder in Kombination mit Strophanthin appliziert, führen bei der Ratte zu einer Erniedrigung des Gesamtcalciumgehaltes des Myocard. Dihydrotachysterol (DHT) erhöht den Calciumgehalt und zeigt elektronenmikroskopisch SchÄdigungen an Mitochondrien und Myofibrillen. Die kombinierte Gabe von DHT und Noradrenalin bzw. Angiotensin potenziert den Calciumwert, erhöht das Magnesium und lÄ\t Kalium nahezu unverÄndert. Die im Bereich der linksventrikulÄren Innenschichten ausgebildeten „Catecholaminnekrosen“ finden sich nach DHT-PrÄmedikation ubiquitÄr. Strophanthin verhindert den massiven, durch DHT- und Angiotensinmedikation induzierten Calciumstieg, wÄhrend es bei der kombinierten Gabe von DHT und Noradrenalin keine Wirkung entfaltet. Myofibrillen und Mitochondrien sind verÄndert, Calciumablagerungen sind nachweisbar, charakteristische Unterschiede fehlen.
Notes:
Summary Changes in certain tissue electrolytes brought about by injecting rats with noradrenalin (NA), angiotensin or dihydrotachysterol (DHT) were compared with the concomitant ultrastructural alterations of cardiac muscle. High doses of NA or angiotensin given singly or together with ouabain were found to lower the overall myocardial calcium concentration without accompanying structural lesions. When calcium was increased more than tenfold by the administration of DHT, electronmicroscopy revealed altered myofibrils and mitochondria. Giving DHT along with NA or angiotensin not only preserved their calcium-lowering effect, but resulted in a massive increase in tissue calcium, with magnesium levels also rising, whilst the tissue content of potassium remained almost unchanged. Following NA administration the necrotic areas, known to be confined to the inner endocardial layer after catecholamine administration, pervaded the entire cardiac muscle mass. Ouabain prevented the massive rises of tissue calcium induced by DHT given together with angiotensin but was ineffective when added to the combination of DHT and NA. In either case, both myofibrils and mitochondria displayed ultrastructural alterations although distinctive features were lacking. The data suggests that DHT acts on cellular calcium, not only by mobilising calcium from osseous structures but also by interacting with intracellular calcium homeostasis. In addition to overstimulating contractile elements, calcium is thought to exert its noxious effect in a more generall way, e.g. by binding to surface membranes, thus affecting the normal functioning and eventually the structure of mitochondria and other organelles besides myofibrils.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00427063
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