Journal
AMERICAN JOURNAL OF PHYSIOLOGY-HEART AND CIRCULATORY PHYSIOLOGY
Volume 285, Issue 5, Pages H2158-H2164Publisher
AMER PHYSIOLOGICAL SOC
DOI: 10.1152/ajpheart.00086.2003
Keywords
fatty acids; glucose; oxidation; heart; catecholamine
Funding
- NATIONAL CENTER FOR RESEARCH RESOURCES [S10RR014778, M01RR000036] Funding Source: NIH RePORTER
- NATIONAL HEART, LUNG, AND BLOOD INSTITUTE [R01HL058878, P01HL013851] Funding Source: NIH RePORTER
- NATIONAL INSTITUTE ON AGING [R01AG012822] Funding Source: NIH RePORTER
- NCRR NIH HHS [S10 RR 14778, M01 RR 00036] Funding Source: Medline
- NHLBI NIH HHS [P01 HL 13851, R01 HL 58878] Funding Source: Medline
- NIA NIH HHS [R01 AG 12822] Funding Source: Medline
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In humans, under resting conditions there is an age-related decrease in myocardial fatty acid utilization (MFAU) and oxidation (MFAO) and a relative increase in myocardial glucose utilization (MGU). The impact of age on an individual's myocardial metabolic response to catecholamines is not well defined. Sixteen younger (mean age, 26 +/- 5 yr) and 14 older (mean age, 69 +/- 4 yr) volunteers underwent positron emission tomography to measure myocardial blood flow, myocardial oxygen consumption (M(V) over dot O-2), MFAU, MFAO, and MGU both under resting conditions and during dobutamine infusion. In response to dobutamine administration, the rate-pressure product, myocardial blood flow, and M(V) over dot O-2 measurements increased by similar amounts in both groups. No age-related differences were noted in the responses of plasma insulin, glucose, fatty acid, or lactate levels to dobutamine. With dobutamine infusion, MFAU and MFAO increased by a similar extent in both younger and older volunteers (age/dobutamine interactions, P = 0.62 and 0.75, respectively). In contrast, MGU increased with dobutamine administration in the younger (from 149 +/- 71 to 209 +/- 78 nmol.g(-1).min(-1); P = 0.04) but not in the older (from 235 +/- 147 to 176 +/- 84 nmol.g(-1).min(-1); P = 0.23; age/dobutamine interaction, P = 0.03) group. With dobutamine infusion, hearts in both younger and older volunteers responded by increasing their MFAU and MFAO values. Whereas younger hearts also responded with an increase in MGU, older hearts did not. Although the clinical significance of these findings awaits further study, these results may partially explain the impaired contractile reserve and the increased incidence of cardiovascular disease in older individuals.
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