Key result
During maximal isoproterenol stimulation, the increase in maximum rate of force development was 40% less in senescent rat hearts compared to adult hearts, despite similar protein kinase activation.
The diminished contractile response to catecholamines in senescent hearts appears to be mediated by factors acting subsequent to protein kinase activation but proximal to the calcium-troponin interaction.
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Suggests post-PKA defects impair inotropic reserve in aging hearts; leaves open human relevance and therapeutic targets.
Guarnieri et al. (1980) studied Age dependence of myocardial contractile performance. Isoproterenol, dibutyryl cAMP, and increased calcium vs. Adult vs senescent hearts / basal state was evaluated on Maximum rate of force development (dF/dt) and biochemical parameters. During maximal isoproterenol stimulation, the increase in maximum rate of force development was 40% less in senescent rat hearts compared to adult hearts, despite similar protein kinase activation.
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