Directed endoscopic mucosal mapping of normal and dysrhythmic gastric slow waves in healthy humans.

Frequency and amplitude characteristics of normal and dysrhythmic slow waves in different gastric regions are poorly characterized. Using endoscopic mucosal mapping, we quantified slow wave frequency and power at predetermined sites under control conditions and with glucagon. Twelve healthy volunteers underwent gastroscopy with midazolam. Bipolar recording electrodes were directed to 12, 7, and 2 cm proximal to the pylorus along the greater and lesser curvatures. Dominant frequencies at all sites were 2.96 +/- 0.07 cycles min(-1) (cpm). Powers of the dominant frequency were 59 +/- 7% lower 12 cm vs 2 cm from the pylorus (P < 0.01), but were similar along the greater and lesser curvatures. Glucagon (0.3 mg IV) decreased dominant frequencies (1.40 +/- 0.10 cpm, P < 0.01) and elicited power reductions which varied by region (36 +/- 37% at 12 cm vs 79 +/- 20% at 2 cm, P < 0.01). Comparing dominant frequencies from mucosal recordings and electrogastrography revealed minimal slow wave uncoupling. In conclusion, endoscopic mucosal mapping demonstrates slow wave power gradients from the proximal to distal stomach under normal conditions. Glucagon evokes bradygastria with minimal uncoupling and elicits inhibitory effects on slow wave power which are more potent in the distal antrum. This method provides insight into the mechanisms of action of gastric slow wave dysrhythmic stimuli.