Postprandial hypotension in response to duodenal glucose delivery in healthy older subjects

Abstract

Postprandial hypotension occurs frequently in older people and may lead to syncope and falls. Some recent studies suggest that the magnitude of the postprandial fall in blood pressure (BP) is influenced by the rate of gastric emptying. The aim of this study was, therefore, to determine whether the fall in blood pressure induced by intraduodenal glucose is influenced by the rate of nutrient delivery into the small intestine, bypassing the effects of gastric emptying. Eight healthy elderly subjects (four male and four female, age 70.3 +/- 3.4 years) were studied on two separate days, in double-blind, randomised order. Glucose was infused intraduodenally at a rate of either 1 or 3 kcal min(-1), for 60 min, (0-60 min) followed by 0.9 % saline for a further 60 min (60-120 min). Blood pressure and heart rate were recorded at baseline and every 3 min during the study. Blood glucose and plasma insulin were also determined. Only the 3 kcal min(-1) infusion caused a significant fall in systolic (P < 0.001) and diastolic (P < 0.0001) blood pressure and an increase in the heart rate (P < 0.0001). The rises in blood glucose (P < 0.01) and plasma insulin (P < 0.05) concentrations were greater during the 3 kcal min(-1) infusion. We conclude that in healthy older subjects, the magnitude of the fall in blood pressure and increase in heart rate induced by intraduodenal glucose infusion is dependent on the rate of nutrient delivery into the small intestine. These results may have relevance to the treatment of postprandial hypotension.

Figures

Figure 1. Effect of intraduodenal glucose infusion at a rate of either 1 kcal min−1 (•) or 3 kcal min−1 (▵) on systolic blood pressure (top graph), diastolic blood pressure (middle graph) and heart rate (bottom graph)

Data are presented as changes from baseline and are means ±s.e.m. Significant differences: *change from baseline for 1 kcal min−1; **change from baseline for 3 kcal min−1 and #3 kcal min−1vs. 1 kcal min−1 over time.

Figure 2. Effect of intraduodenal glucose infusion at a rate of either 1 kcal min−1 (left) or 3 kcal min−1 (right) on systolic blood pressure

Individual raw data are presented at 0 and 60 min.

Figure 3. Effect of intraduodenal glucose infusion at a rate of either 1 kcal min−1 (•) or 3 kcal min−1 (▵) on blood glucose (left) and plasma insulin (right) concentrations (absolute values)

Data are means ±s.e.m. Significant differences: *change from baseline for 1 kcal min−1; ** change from baseline for 3 kcal min−1 and #3 kcal min−1vs. 1 kcal min−1 over time.