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Do changes in gastro‐intestinal blood flow explain high‐altitude anorexia?
Author(s) -
Kalson Nicholas S.,
Hext Faye,
Davies Andrew J.,
Chan Colin W. M.,
Wright Alex D.,
Imray Christopher H. E.
Publication year - 2010
Publication title -
european journal of clinical investigation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.164
H-Index - 107
eISSN - 1365-2362
pISSN - 0014-2972
DOI - 10.1111/j.1365-2362.2010.02324.x
Subject(s) - blood flow , medicine , superior mesenteric artery , hemodynamics , cardiology , sma* , effects of high altitude on humans , endocrinology , gastroenterology , anatomy , combinatorics , mathematics
Eur J Clin Invest 2010; 40 (8): 735–741 Abstract Background Gastrointestinal symptoms are common on acute exposure to high‐altitude (HA). Underlying mechanisms are not understood, but vascular shunting away from the gut could be responsible. Therefore, blood flow in the superior mesenteric artery (SMA) and hepatic portal vein (HPV) was examined at sea level (SL) and after ascent to 4392 m (HA). Materials and methods Twelve subjects [eight male, mean age 40 (22–72) years] were studied following an overnight fast and a standard meal. Cross‐sectional vessel area and blood velocity were measured by ultrasound, systolic and diastolic flow calculated for the SMA (HR × vessel area × velocity, cm 3 min −1 ) and mean flow for the HPV. Results All subjects experienced reduced appetite at HA. Blood flow in the SMA and HPV increased following food at SL (mean SMA systolic flow 1024 vs. 3316 cm 3 min −1 , P < 0·001; HPV 505 vs. 1789, P < 0·001) and at HA (2020 vs. 3767, P < 0·001; HPV 708 vs. 1727, P < 0·001). Pre‐prandial flow in the SMA and HPV was significantly increased at HA compared with SL. The changes were due to increased vessel diameter and increased flow velocity. There was no difference in post‐prandial flow between SL and HA in the HPV, although the increase in post‐prandial flow was greater at SL than HA (254% increase vs. 144%). Conclusions These results show that resting blood flow in the gastrointestinal tract is increased during exposure to high‐altitude hypoxia, and that the vascular response of increased blood flow following food ingestion is maintained. Therefore, reduced flow is unlikely to cause gastrointestinal symptoms and reduced appetite at HA.