Objective: To examine the relationship between postprandial superior mesenteric arterial blood flow (SMABF) and endogenous gastrointestinal hormone secretion after liquid meals of varying energy content.
Methods: Six healthy volunteers received four isovolumetric meals of differing energy content. SMABF was measured before and for 120 min after feeding using duplex ultrasound; plasma levels of gastrointestinal hormones and noradrenaline were measured.
Results: Results are given as means +/- SEM. Postprandial SMABF increased after each meal; the peak mean percentage increment occurred at 28 +/- 8 min, varying from 106 +/- 26% (P < 0.05) with the 800 kj meal to 240 +/- 62% (P < 0.05) with the 4800 kj meal. The rise was sustained and correlated with energy content (r = 0.969; P = 0.031). The subjects' pulse rate increased after each meal and the increment appeared to be related to meal size (r = 0.990; P = 0.008). Blood pressure did not change. The postprandial concentration of N-terminal neurotensin peaked between 30 and 120 min. The mean peak concentration increased from a baseline value of 30.9 +/- 3.5 ng/l by 19.3 ng/l after 800 kj, 31 ng/l after 1600 kj, 38 ng/l after 2400 kj and 64.3 ng/l after the 4800 kj meal (all differences P < 0.05). The rise was sustained and correlated with energy content (r = 0.967; P = 0.033). Plasma noradrenaline concentration also increased significantly after each meal and was related to energy content (r = 0.90; P = 0.036). Plasma insulin concentration showed a similar postprandial response but had no relationship to energy content. Gastrin concentration increased transiently but changes in the concentration of glucagon, vasoactive intestinal polypeptide and neurokinin A were not significant.
Conclusions: The results indicate a relationship between meal energy content, postprandial SMABF and pulse rate increments. Postprandial increases in N-terminal neurotensin and noradrenaline concentration were also related to energy content and may indicate a role for these hormones in the control of SMABF after feeding.