. Effects of drink volume and glucose load on gastric emptying and postprandial blood pressure in healthy older subjects. Am J Physiol Gastrointest Liver Physiol 289: G240 -G248, 2005. First published March 17, 2005 doi:10.1152/ajpgi.00030.2005.-Postprandial hypotension (PPH) occurs frequently in the elderly; the magnitude of the fall in blood pressure (BP) is related to the rate of glucose entry into the duodenum during intraduodenal glucose infusion and spontaneous gastric emptying (GE). It is unclear if glucose concentration affects the hypotensive response. Gastric distension may attenuate PPH; therefore, meal volume could influence the BP response. We aimed to determine the effects of 1) drink volume, 2) glucose concentration, and 3) glucose content on the BP and heart rate (HR) responses to oral glucose. Ten subjects (73.9 Ϯ 1.2 yr) had measurements of BP, GE, and blood glucose on 4 days after 1) 25 g glucose in 200 ml (12.5%), 2) 75 g glucose in 200 ml (37.5%), 3) 25 g glucose in 600 ml (4%), and 4) 75 g glucose in 600 ml (12.5%). GE, BP, HR, and blood glucose were measured for 180 min. After all drinks, duodenal glucose loads were similar in the first 60 min. Regardless of concentration, 600-ml (but not 200-ml) drinks initially increased BP, and in the first 30 min, systolic BP correlated (P Ͻ 0.01) with volume in both the proximal and total stomach. At the same concentration (12.5%), systolic BP fell more (P ϭ 0.02) at the smaller volume; at the same volumes, there were no effects of concentration on BP. There was no difference in the glycemic response to drinks of identical glucose content. We conclude that 1) ingestion of glucose at a higher volume attenuates and 2) under constant duodenal load, glucose concentration (4 -37%) does not affect the fall in BP. postprandial hypotension; gastric emptying; elderly POSTPRANDIAL HYPOTENSION, leading to syncope and falls, is an important clinical problem, particularly in the elderly and patients with autonomic dysfunction (7,12,14,19). The mechanisms responsible for postprandial hypotension are poorly defined, and current treatments are less than optimal (7,12,14,19). The magnitude of the postprandial fall in blood pressure is known to be dependent on meal compositioningestion of carbohydrate, particularly glucose, has the greatest effect on blood pressure (27), whereas the effects of fat and protein appear to be much less (10).Changes in splanchnic blood flow, sympathetic nerve activity, and release of gastrointestinal peptides are all thought to play a role in postprandial hypotension (7,12,14,19). Onset of the fall in blood pressure is evident soon after a meal, with a maximum response at 30 -60 min (14). While oral ingestion of glucose leads to a fall in blood pressure, intravenous infusion of glucose has little, if any, effect (13) indicating that the response is mediated from the gastrointestinal tract. We have reported that in both healthy older subjects and patients with type 2 diabetes managed by diet alone, the hypotensive and heart rate responses t...