Adrenergic modulation of small bowel haemodynamics in interdigestive motility state of man.
OBJECTIVE
We previously reported a new application of semi-invasive laser-Doppler flowmetry (LDF) to record small intestinal haemodynamics in man under basal motor conditions, i.e. during phase I of the migrating motor complex (MMC). In the present study, we evaluated the complete MMC cycle and its haemodynamics in humans; specifically, adrenergic influence on blood flow in all three MMC phases was studied.


METHODS
Twenty-one fasting healthy male volunteers (21-44 years) were studied during two complete MMC cycles: the first as control period, the second as experimental period with different adrenergic drugs or saline.


METHODS
Recording of LDF of intestinal blood flow was performed by attaching two single-fibre microprobes to a small intestinal manometry tube, which simultaneously monitored luminal pressure changes.


RESULTS
Clonidine and oxymetazoline, two alpha2-adrenoceptor agonists, significantly decreased blood flow during all phases of the MMC cycle. In contrast, the non-selective beta-adrenoceptor agonist isoprenaline induced phase II-like activity with a significant increase in blood flow. Propranolol, a beta-adrenoceptor antagonist, did not alter motility but decreased blood flow throughout the MMC cycle.


CONCLUSIONS
Both alpha- and beta-adrenergic mechanisms modifying small bowel haemodynamics are in operation throughout phases I, II and III of MMC. Our findings support the use of the semi-invasive LDF technique to measure drug-induced haemodynamic changes in the fasting gut.
Thollander
M
M
Department of Medicine, Karolinska Hospital, Stockholm, Sweden.
Gazelius
B
B
Hellström
P M
PM
D000316:Adrenergic alpha-Agonists / Q000494:pharmacology; D000318:Adrenergic beta-Agonists / Q000494:pharmacology; D000319:Adrenergic beta-Antagonists / Q000494:pharmacology; D000328:Adult; D003000:Clonidine / Q000494:pharmacology; D004386:Duodenum / Q000098:blood supply / Q000187:drug effects / Q000502:physiology*; D005215:Fasting; D005769:Gastrointestinal Motility / Q000187:drug effects / Q000502:physiology*; D006439:Hemodynamics / Q000187:drug effects / Q000502:physiology; D006801:Humans; D007545:Isoproterenol / Q000494:pharmacology; D007583:Jejunum / Q000098:blood supply / Q000187:drug effects / Q000502:physiology*; D017078:Laser-Doppler Flowmetry; D008297:Male; D008365:Manometry / Q000295:instrumentation; D016065:Myoelectric Complex, Migrating / Q000187:drug effects / Q000502:physiology*; D010109:Oxymetazoline / Q000494:pharmacology; D011312:Pressure; D011433:Propranolol / Q000494:pharmacology; D011941:Receptors, Adrenergic / Q000187:drug effects / Q000502:physiology*; D012039:Regional Blood Flow / Q000187:drug effects / Q000502:physiology
D000316:Adrenergic alpha-Agonists; D000318:Adrenergic beta-Agonists; D000319:Adrenergic beta-Antagonists; D011941:Receptors, Adrenergic; D010109:Oxymetazoline; D011433:Propranolol; D007545:Isoproterenol; D003000:Clonidine