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Effect of age on presynaptic beta 2 receptor mediated responses in the rat heart
Journal article   Peer reviewed

Effect of age on presynaptic beta 2 receptor mediated responses in the rat heart

Mary L. Mortimer, Nihal Tumer, Mark D. Johnson, Jay Roberts and James R Roberts
Mechanisms of ageing and development, v 59(1)
1991

Abstract

Beta adrenoceptor Fischer 344 rat Presynaptic receptor
Presynaptic alpha 2 adrenergic receptor inhibition of norepinephrine (NE) release is diminished in older animals [1]. To determine whether presynaptic beta 2 adrenergic receptor facilitation of NE release is also affected by age, the effect of propranolol on neurally-induced NE release was examined in perfused heart preparations isolated from 6- and 24-month-old rats. The heart was isolated with the right cardiac sympathetic nerve and then was stimulated electrically in the absence and presence of propranolol (10 −8–10 −6 M). NE content in the effluent was measured by an HPLC/EC methodology. The data indicate that there is a greater suppression of NE release by propranolol in preparations isolated from younger animals. For example, in nerve-heart preparations of 6-month-old animals stimulated at 12 Hz, propranolol (10 −6M) reduced the amount of NE released by 34% whereas in preparations from 24-month-old animals at 12 Hz there was no significant change in the NE overflow. Like the alpha 2 receptor mechanism, autoregulation of NE release by presynaptic beta 2 receptors is diminished in older animals. Lack of presynaptic autoregulation may explain in part, the reduced capacity of adrenergic influences to control and regulate cardiac function in older animals.

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Collaboration types
Domestic collaboration
Web of Science research areas
Cell Biology
Geriatrics & Gerontology
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