Possibility of postprandial electrogastrography for evaluating vagal/nonvagal cholinergic activity in humans, through simultaneous analysis of postprandial heart rate variability and serum immunoreactive hormone levels.

Abstract

To investigate changes in postprandial electrogastrography (EGG) from the neurohormonal mechanisms. We measured EGG indices [frequency amplitude of normal 3-cpm (EGG-3 cpm)], high frequency amplitude of heart rate variability which has reflected cardiac parasympathetic tone, and several serum immunoreactive (ir)-hormone levels in 12 fasted male volunteers (mean age 25.3 yr). Immediately after the liquid food intake (250 kcal), a transient decrease in EGG-3 cpm frequency (from 0.045 +/- 0.001 Hz to 0.040 +/- 0.001 Hz; p < 0.05) accompanied by an increase in high frequency amplitude (from 31.05 +/- 3.45 ms to 39.10 +/- 4.08 ms; p < 0.05), and a serum immunoreactive gastrin level increase (from 38.72 +/- 4.92 pmol/L to 54.00 +/- 10.45 pmol/L; p < 0.05) and an immunoreactive somatostatin level decrease (from 15.00 +/- 0.43 pmol/L to 13.70 +/- 0.46 pmol/L; p < 0.01) were observed, suggesting vagal excitement. EGG-3 cpm amplitude and serum immunoreactive human pancreatic polypeptide (hPP) levels significantly increased soon after ingestion, and these changes lasted for 30 min. Furthermore, there was a positive correlation between changes in EGG-3 cpm amplitude and those in serum immunoreactive hPP levels during the postprandial periods (r = 0.55, p < 0.001). Considering the reports that a cholinergic, nonvagal pathway is of major importance in food-stimulated hPP release, the present results suggest that postprandial changes in EGG-3 cpm frequency and amplitude might be a good tool for evaluating not only vagal but also nonvagal cholinergic activity in the human gut.