In young adult humans, acute energy intake (feeding) evokes an integrative """"""""postprandial"""""""" physiological response which includes an increase in metabolic rate (thermic effect of food intake--TEF) and a number of autonomic nervous system (ANS) and cardiovascular adjustments aimed at providing increased blood flow for digestion (splanchnic vasodilation) while maintaining arterial blood pressure (BP) at preprandial levels. Some older adults with chronic diseases demonstrate a reduced TEF and/or a postprandial fall in BP (""""""""postprandial hypotension""""""""), but it is unknown whether this occurs with age in healthy adults. If the latter is true, some evidence suggests that these changes may not occur with age in adult humans who exercise regularly.
The specific aims of the present proposal are to determine if: (1) TEF is lower and postprandial BP declines occur in middle-aged and/or older sedentary adults compared with young adult controls; (2) the lower TEF is due to attenuated postprandial increases in sympathetic nervous system (SNS) activity associated with reduced CNS sympathoexcitatory responsiveness to acute hyperinsulinemia; (3) the postprandial hypotension also is associated with: a) an attenuated or absent whole-limb and skeletal muscle vasoconstriction; b) a smaller reduction in cardiac vagal modulation of heart rate and an attenuated tachycardia; and c) a lower baseline cardiac vagal tone and arterial baroreflex sensitivity; (4) middle-aged and older adults who exercise regularly do not demonstrate the lower TEF and postprandial hypotension observed with age in sedentary humans, and whether this is associated with augmented SNS responses, CNS sympathetic responsiveness to circulating insulin, limb vasoconstriction, vagally-mediated tachycardia, baseline cardiac vagal tone and baroreflex sensitivity; and (5) the reduced TEF and postprandial hypotension associated with sedentary aging are related to elevated adiposity. Because TEF contributes significantly to daily energy expenditure and, therefore, energy balance, the expected results should provide new and clinically important information concerning the effects of sedentary aging, regular exercise and adiposity on TEF in the context of age-related obesity and its metabolic and cardiovascular co-morbidities. Moreover, postprandial hypotension is associated with post-meal dizziness, weakness, syncope, cerebrovascular ischemia, and angina pectoris. As such, the expected results should provide new insight into the effects of sedentary aging, habitual exercise and body fatness on this clinically-important cardiovascular disorder.

National Institute of Health (NIH)
National Institute on Aging (NIA)
Research Project (R01)
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Respiratory and Applied Physiology Study Section (RAP)
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Dutta, Chhanda
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University of Colorado at Boulder
Schools of Arts and Sciences
United States
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Christou, Demetra D; Pierce, Gary L; Walker, Ashley E et al. (2012) Vascular smooth muscle responsiveness to nitric oxide is reduced in healthy adults with increased adiposity. Am J Physiol Heart Circ Physiol 303:H743-50
Jablonski, Kristen L; Chonchol, Michel; Pierce, Gary L et al. (2011) 25-Hydroxyvitamin D deficiency is associated with inflammation-linked vascular endothelial dysfunction in middle-aged and older adults. Hypertension 57:63-9
Gano, Lindsey B; Donato, Anthony J; Pierce, Gary L et al. (2011) Increased proinflammatory and oxidant gene expression in circulating mononuclear cells in older adults: amelioration by habitual exercise. Physiol Genomics 43:895-902
Walker, Ashley E; Seibert, Sara Marian; Donato, Anthony J et al. (2010) Vascular endothelial function is related to white blood cell count and myeloperoxidase among healthy middle-aged and older adults. Hypertension 55:363-9
LaRocca, Thomas J; Seals, Douglas R; Pierce, Gary L (2010) Leukocyte telomere length is preserved with aging in endurance exercise-trained adults and related to maximal aerobic capacity. Mech Ageing Dev 131:165-7
Seals, Douglas R; Walker, Ashley E; Pierce, Gary L et al. (2009) Habitual exercise and vascular ageing. J Physiol 587:5541-9
Lesniewski, Lisa A; Connell, Melanie L; Durrant, Jessica R et al. (2009) B6D2F1 Mice are a suitable model of oxidative stress-mediated impaired endothelium-dependent dilation with aging. J Gerontol A Biol Sci Med Sci 64:9-20
Pierce, Gary L; Lesniewski, Lisa A; Lawson, Brooke R et al. (2009) Nuclear factor-{kappa}B activation contributes to vascular endothelial dysfunction via oxidative stress in overweight/obese middle-aged and older humans. Circulation 119:1284-92
Stob, Nicole R; Seals, Douglas R; Jorgen, Jensen et al. (2007) Increased thermogenic responsiveness to intravenous beta-adrenergic stimulation in habitually exercising humans is not related to skeletal muscle beta2-adrenergic receptor density. Exp Physiol 92:823-30
Stob, Nicole R; Bell, Christopher; van Baak, Marleen A et al. (2007) Thermic effect of food and beta-adrenergic thermogenic responsiveness in habitually exercising and sedentary healthy adult humans. J Appl Physiol 103:616-22

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