Effects of drink volume and glucose load on gastric emptying and postprandial blood pressure in healthy older subjects

Abstract

. 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...

Hemodynamic effects of liquid food ingestion in mid-thoracic paraplegia: is supine postprandial hypotension related to thoracic spinal cord damage?

“…However, this effect was manifested with a 600 ml but not with a 200 ml fluid load, 20 and the 300 ml fluid load of the meal in the present experiment is unlikely to have had different effects, if any, on the study groups.…”

“…Gastric distension by the volume of the fluid-meal, which increases BP in healthy people, 20 more so in older than in younger ones, 21 could also have attenuated the drop in BP in tetraplegia. However, this effect was manifested with a 600 ml but not with a 200 ml fluid load, 20 and the 300 ml fluid load of the meal in the present experiment is unlikely to have had different effects, if any, on the study groups.…”

Effects of variations in intragastric volume on blood pressure and splanchnic blood flow during intraduodenal glucose infusion in healthy older subjects

“…There is persuasive evidence that gastric distension plays a protective role in the maintenance of postprandial blood pressure (5,10,19,21,22,35,38,44,46). Consumption of 480 ml of water increases systolic blood pressure in healthy older subjects, as well as patients with multiple-system atrophy and autonomic failure (21), and attenuates the fall in blood pressure induced by a high-carbohydrate meal in patients with autonomic failure (38).…”

“…Consumption of 480 ml of water increases systolic blood pressure in healthy older subjects, as well as patients with multiple-system atrophy and autonomic failure (21), and attenuates the fall in blood pressure induced by a high-carbohydrate meal in patients with autonomic failure (38). In healthy older subjects, the magnitude of the fall in systolic blood pressure is known to be greater when glucose is ingested at a smaller volume (200 vs. 600 ml) at the same glucose concentration (19). Using a barostat balloon set to 8 mmHg above MDP, we reported previously (46), also in healthy older subjects, that gastric distension prevented the fall in blood pressure induced by intraduodenal glucose given at a rate of 3 kcal/min.…”

Roles of the Gut in Glucose Homeostasis

“…The rate of gastric emptying usually is relatively unaffected by the volume of the meal. Accordingly, meals with a higher nutrient content take longer to empty, but they empty at a similar rate when expressed as kilocalories per minute (17). Therefore, in experiments with increasing amounts of glucose (25-75-125 g) ingested in the same volume, peak absorption estimated from the liquid phase marker acetaminophen was delayed from 30 to 90 and 180 min, respectively (5).…”