Insulin-induced hypoglycemia stimulates gastric vagal activity and motor function without increasing cardiac vagal activity.
OBJECTIVE
We investigated whether increasing the efferent vagal activity by insulin-induced hypoglycemia would enhance gastric emptying and volumes in healthy subjects.


METHODS
Twenty healthy volunteers (10 males) were examined with and without vagal stimulation by insulin-induced hypoglycemia using a glucose clamp technique. Stomach function was tested by drinking meat soup (0.04 kcal ml(-1)) at a rate of 100 ml min(-1) until maximal capacity. Intragastric volume at maximal drinking capacity was determined by three-dimensional ultrasound. Respiratory sinus arrhythmia (RSA) was used as an index of cardiac vagal activity and plasma pancreatic polypeptide (PP) as a measure of gastric vagal activity, and skin conductance (SC) as a measure of sympathetic tone.


RESULTS
Insulin-induced hypoglycaemia increased drinking capacity (p = 0.002), gastric emptying (p = 0.02), PP (p = 0.004) and SC (p = 0.004), while intragastric volume was unchanged (p = 0.7) and RSA decreased (p = 0.03).


CONCLUSIONS
Enhancement of gastric vagal activity by insulin-induced hypoglycemia increased drinking capacity and gastric emptying similarly, resulting in an unchanged intragastric volume. Enhanced efferent vagal activity to the stomach (as measured by PP) was not associated by enhanced cardiac vagal activity (as measured by RSA), possibly a consequence of stress-induced sympathetic activation during the procedure.
Hjelland
Ina Elen
IE
Institute of Medicine, Haukeland University Hospital, NO-5021 Bergen, Norway. ina.hjelland@med.uib.no
Oveland
Nils Petter
NP
Leversen
Katrine
K
Berstad
Arnold
A
Hausken
Trygve
T
D000328:Adult; D005260:Female; D005712:Galvanic Skin Response; D005746:Gastric Emptying / Q000502:physiology; D006801:Humans; D007003:Hypoglycemia; D007004:Hypoglycemic Agents / Q000494:pharmacology*; D007328:Insulin / Q000494:pharmacology*; D008297:Male; D013270:Stomach / Q000294:innervation*; D014630:Vagus Nerve / Q000502:physiology*
D007004:Hypoglycemic Agents; D007328:Insulin