title: Pharmacological modulation of gut mucosal and large vessel blood flow.
abstract: BACKGROUND
  Constipation, diminished gut blood flow, ischaemic colitis and drug therapy may be associated.
  
  
  OBJECTIVE
  To study the effect of constipating medication on, and the regulation of, gut blood flow.
  
  
  METHODS
  24 healthy females (mean age 30) received, in a double-blind, three-way crossover study: (i) placebo, (ii) ipratropium 40 microg by inhalation (positive control known to reduce rectal mucosal blood flow) and (iii) oral loperamide 4 mg. Mucosal blood flow was measured at the splenic flexure and rectum using laser Doppler flowmetry. Blood flow in the superior and inferior mesenteric arteries was measured by trans-abdominal Doppler ultrasound.
  
  
  RESULTS
  Ipratropium decreased rectal mucosal blood flow by 16% (P=0.009) and splenic flexure mucosal blood flow by 8% (P=0.075). Loperamide caused no change in rectal (P=0.40) or splenic flexure mucosal blood flow (P=0.73). Neither treatment changed superior or inferior mesenteric artery blood flow. Splenic flexure mucosal blood flow showed a positive correlation with rectal mucosal blood flow (r=0.69; P<0.0001).
  
  
  CONCLUSIONS
  Vasoactive agents may reduce gut mucosal blood flow in the absence of reduced large vessel flow. Constipating drugs do not necessarily reduce gut blood flow. Rectal mucosal blood flow correlates with splenic flexure mucosal flow, and potentially may be used as a more convenient surrogate for studying splenic flexure blood flow.
authors.affiliation: St Mark's Hospital, London, UK. kamm@imperial.ac.uk
authors.forename: M A
authors.initials: MA
authors.lastname: Kamm
authors.forename: C C
authors.initials: CC
authors.lastname: Jordan
authors.forename: B R
authors.initials: BR
authors.lastname: Leaker
authors.forename: F B
authors.initials: FB
authors.lastname: Nicholson
authors.forename: C D R
authors.initials: CD
authors.lastname: Murray
authors.forename: S
authors.initials: S
authors.lastname: Taylor
authors.forename: M
authors.initials: M
authors.lastname: Marshall
authors.forename: A
authors.initials: A
authors.lastname: Gibbs
authors.forename: E G
authors.initials: EG
authors.lastname: Carter
authors.forename: A V
authors.initials: AV
authors.lastname: Emmanuel
mesh_terms: D000280:Administration, Inhalation; D000284:Administration, Oral; D000328:Adult; D044684:Colon, Transverse / Q000098:blood supply*; D003248:Constipation / Q000188:drug therapy; D018592:Cross-Over Studies; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D007413:Intestinal Mucosa / Q000098:blood supply; D009241:Ipratropium / Q000494:pharmacology*; D017078:Laser-Doppler Flowmetry; D008139:Loperamide / Q000494:pharmacology*; D017537:Mesenteric Artery, Inferior / Q000187:drug effects; D017538:Mesenteric Artery, Superior / Q000187:drug effects; D008875:Middle Aged; D012007:Rectum / Q000098:blood supply*; D012039:Regional Blood Flow; D013152:Splanchnic Circulation / Q000187:drug effects*
chemical_list: D008139:Loperamide; D009241:Ipratropium