Hyperglycemia alters perception of rectal distention and blunts the rectoanal inhibitory reflex in healthy volunteers.
OBJECTIVE
Acute hyperglycemia has been shown to alter gastrointestinal motility. The effects of hyperglycemia on rectal afferent neural and anal sphincter function were studied.


METHODS
Perception of rectal balloon distention, pressure-volume relationships, volumes necessary to induce reflex internal anal sphincter relaxation, resting anal sphincter pressure, and maximal anal sphincter squeeze pressure were measured under basal, hyperglycemic clamp, and euglycemic, hyperinsulinemic clamp conditions in 9 healthy volunteers.


RESULTS
Hyperglycemic clamping (258 +/- 14 mg/dL) significantly blunted threshold perception and the urge to defecate in response to rectal distention without altering perception of maximally tolerated distention. In contrast, euglycemic, hyperinsulinemic clamping had no effect on perception of rectal distention. Rectal pressure-volume relationships after hyperglycemic clamping were unchanged compared with basal conditions. Hyperglycemic clamping caused a significant increase in the distention necessary to induce the rectoanal inhibitory reflex. This effect was not observed under euglycemic, hyperinsulinemic clamp conditions. Hyperglycemia did not significantly affect resting internal anal sphincter pressure or maximal external anal sphincter squeeze pressure.


CONCLUSIONS
Acute hyperglycemia but not secondary hyperinsulinemia reduces sensation of rectal distention and blunts the onset of the rectoanal inhibitory reflex, suggesting effects both on visceral afferents projecting to the cortex and intrinsic afferents mediating local reflex activity.
Chey
W D
WD
Department of Internal Medicine, University of Michigan Medical Center, Ann Arbor, USA.
Kim
M
M
Hasler
W L
WL
Owyang
C
C
D000328:Adult; D001003:Anal Canal / Q000502:physiology*; D005260:Female; D006801:Humans; D006943:Hyperglycemia / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D010465:Perception; D011312:Pressure; D012007:Rectum / Q000502:physiology*; D012018:Reflex