Splanchnic flow rises by up to 100 per cent for several hours after eating
Expansion
After a meal, splanchnic blood flow rises by 30 to 100 per cent, peaking at 30 to 90 minutes and lasting several hours. Mediated by:
- Gut hormones, particularly cholecystokinin and gastrin
- Local metabolites and absorbed nutrients, especially fat and glucose
- Increased metabolic activity of the mucosa
- Nitric oxide and adenosine
Two clinical consequences:
Postprandial hypotension - blood is redistributed to the gut while compensatory vasoconstriction and heart rate responses are blunted, so blood pressure falls. Common in the elderly, in autonomic failure and in Parkinson disease, and a cause of postprandial falls and syncope. Managed by small, low-carbohydrate meals and avoiding alcohol.
Chronic mesenteric ischaemia - with atherosclerotic stenosis of two or more mesenteric vessels, resting flow is adequate but the postprandial increase cannot be delivered. The result is abdominal angina: dull central pain beginning 15 to 30 minutes after eating, leading to fear of food and weight loss, with an epigastric bruit.