Effect of Age on Potassium-and Tyramine-Induced Release of Norepinephrine From Cardiac Synaptosomes in Male F344 Rats
| Autor: | Jay Roberts, H. Beal McIlvain, David L. Snyder, Mark D. Johnson, Vincent J. Aloyo |
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| Rok vydání: | 1992 |
| Předmět: |
Male
Aging medicine.medical_specialty Potassium Tyramine chemistry.chemical_element Calcium Norepinephrine chemistry.chemical_compound Internal medicine medicine Animals Centrifugation Oxidopamine Synaptosome Atrium (architecture) Chemistry Myocardium Desipramine Proteins Heart Depolarization Rats Inbred F344 Rats Endocrinology Adrenergic Fibers Perfusion Synaptosomes |
| Zdroj: | Journal of Gerontology. 47:B190-B197 |
| ISSN: | 0022-1422 |
| DOI: | 10.1093/geronj/47.6.b190 |
| Popis: | Potassium (K+)-induced norepinephrine (NE) release was examined in preparations of cardiac synaptosomes and sliced atria from 6-, 24-, and 26-mo-old male F344 rats. Cardiac synaptosomes were prepared from rat hearts by collagenase digestion followed by homogenization in 0.32 M sucrose and centrifugation. The synaptosome preparations and the sliced atria were labeled with 3H-NE and then placed in a superfusion system. K(+)-induced net fractional release of NE from synaptosomes prepared from 24- and 26-mo-old rats (4.3% and 3.0%, respectively) was significantly reduced when compared to NE release from synaptosomes from 6-mo-old rats (5.2%). K(+)-induced NE release from sliced atria from 24-mo-old rats (4.7%) was also significantly reduced when compared to NE release from atria from 6-mo-old rats (6.3%). Perfusion of cardiac synaptosomes with buffer prepared without calcium (CA++free, < 5 microM) reduced K(+)-induced release by 50% in all age groups studied. Perfusion with tyramine induced identical rates of NE release from cardiac synaptosomes prepared from 6- and 24-mo-old rats. These results confirm that depolarization-induced NE release from cardiac sympathetic nerves is reduced in the old male F344 rat. |
| Databáze: | OpenAIRE |
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