Effects of the divalent cation ionophore ionomycin on the performance of isolated guinea-pig atria
| Autor: | M. Siess, Himmel Hm, Riehle R, K. Stieler |
|---|---|
| Rok vydání: | 1990 |
| Předmět: |
Male
Chronotropic medicine.medical_specialty Nifedipine Physiology Guinea Pigs Mepyramine Ionophore chemistry.chemical_element Calcium chemistry.chemical_compound Oxygen Consumption Heart Rate Physiology (medical) Internal medicine medicine Animals Heart Atria Pindolol Pyrilamine Ryanodine Ryanodine receptor Ionomycin Heart Atrial Function Myocardial Contraction Stimulation Chemical Sarcoplasmic Reticulum Endocrinology chemistry cardiovascular system Cimetidine Cardiology and Cardiovascular Medicine medicine.drug |
| Zdroj: | Basic Research in Cardiology. 85:247-256 |
| ISSN: | 1435-1803 0300-8428 |
| DOI: | 10.1007/bf01907113 |
| Popis: | In isolated electrically driven left and in spontaneously beating right guinea-pig atria, the calcium ionophore ionomycin produced a concentration-dependent positive inotropic and chronotropic effect with a threshold near 10(-7) mol/l and a pD2 of 6.31 +/- 0.09 and 5.94 +/- 0.07, respectively. At low [Ca2+]o (0.5 mmol/l), the positive inotropic effect of ionomycin (3 X 10(-6) mol/l) was strongly attenuated by ryanodine and nifedipine, and slightly attenuated by pindolol and mepyramine; atropine had no effect. The positive chronotropic effect of ionomycin was slightly reduced by cimetidine or pindolol, whereas atropine, nifedipine, and ryanodine showed no inhibitory activity. The oxygen consumption of resting left atria was significantly enhanced by addition of ionomycin. It is concluded that the action of ionomycin involves at least the following mechanisms: I) release of Ca2+ from sarcoplasmic reticulum, II) influx of Ca2+ from the extracellular space, and, having little significance, III) release of catecholamines and histamine from sympathetic nerve endings and tissue mast cells. However, additional mechanisms of action of ionomycin cannot be excluded. |
| Databáze: | OpenAIRE |
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