OBJECTIVE: The cardiovascular response to a meal is modulated by gastric distension and the interaction of nutrients, particularly carbohydrate, within the small intestine. We tested the hypothesis that the depressor effect of small intestinal glucose is greater in older than in young subjects, because the reflex increase in muscle sympathetic nerve activity (MSNA) is blunted by age. METHODS: The effects of intraduodenal glucose infusion (IDGI) on blood pressure, heart rate and MSNA were evaluated in eight healthy young subjects (4 women; mean age +/- SEM: 28.8 +/- 3.4 years), eight healthy elderly (4 women; 75.3 +/- 1.6 years) and in two patients with symptomatic postprandial hypotension (PPH), one young (21 years), and one old (90 years). RESULTS: In both young and elderly healthy subjects, IDGI decreased blood pressure (P < 0.05), but the fall in systolic blood pressure was greater in the older subjects (-17.0 +/- 4.1 vs. -6.5 +/- 1.6 mmHg, P < 0.03). MSNA increased similarly, after infusion in both young (9.0 +/- 3.4 bursts/min) and elderly (7.8 +/- 1.0 bursts/min) subjects. Baroreflex sensitivity for number of sympathetic bursts was attenuated in the elderly (P < 0.03). The increase in burst area in the young patient with PPH was attenuated (18 vs. 63% in the healthy young group). INTERPRETATION: The fall in BP induced by IDGI was greater in healthy elderly compared to healthy young subjects. The reason for this is unclear, as they have similar increases in MSNA.
OBJECTIVE: The cardiovascular response to a meal is modulated by gastric distension and the interaction of nutrients, particularly carbohydrate, within the small intestine. We tested the hypothesis that the depressor effect of small intestinal glucose is greater in older than in young subjects, because the reflex increase in muscle sympathetic nerve activity (MSNA) is blunted by age. METHODS: The effects of intraduodenal glucose infusion (IDGI) on blood pressure, heart rate and MSNA were evaluated in eight healthy young subjects (4 women; mean age +/- SEM: 28.8 +/- 3.4 years), eight healthy elderly (4 women; 75.3 +/- 1.6 years) and in two patients with symptomatic postprandial hypotension (PPH), one young (21 years), and one old (90 years). RESULTS: In both young and elderly healthy subjects, IDGI decreased blood pressure (P < 0.05), but the fall in systolic blood pressure was greater in the older subjects (-17.0 +/- 4.1 vs. -6.5 +/- 1.6 mmHg, P < 0.03). MSNA increased similarly, after infusion in both young (9.0 +/- 3.4 bursts/min) and elderly (7.8 +/- 1.0 bursts/min) subjects. Baroreflex sensitivity for number of sympathetic bursts was attenuated in the elderly (P < 0.03). The increase in burst area in the young patient with PPH was attenuated (18 vs. 63% in the healthy young group). INTERPRETATION: The fall in BP induced by IDGI was greater in healthy elderly compared to healthy young subjects. The reason for this is unclear, as they have similar increases in MSNA.
Authors: Diana Gentilcore; Belynda Bryant; Judith M Wishart; Howard A Morris; Michael Horowitz; Karen L Jones Journal: Am J Med Date: 2005-11 Impact factor: 4.965
Authors: J H Lavin; G A Wittert; J Andrews; B Yeap; J M Wishart; H A Morris; J E Morley; M Horowitz; N W Read Journal: Am J Clin Nutr Date: 1998-09 Impact factor: 7.045
Authors: P P Jones; L F Shapiro; G A Keisling; J Jordan; J R Shannon; R A Quaife; D R Seals Journal: Circulation Date: 2001-11-13 Impact factor: 29.690
Authors: Deirdre O'Donovan; Christine Feinle-Bisset; Chilton Chong; Alexander Cameron; Anne Tonkin; Judith Wishart; Michael Horowitz; Karen Louise Jones Journal: J Gerontol A Biol Sci Med Sci Date: 2005-07 Impact factor: 6.053
Authors: Laurence G Trahair; Sharmalar Rajendran; Renuka Visvanathan; Matthew Chapman; Daniel Stadler; Michael Horowitz; Karen L Jones Journal: Physiol Rep Date: 2017-07