Dopaminergic control of gastric mucosal blood flow in humans. A study with endoscopic laser Doppler flowmetry coupled with gastric submucosal drug injection.

We studied the dopaminergic regulation of the gastric mucosal blood flow (GMBF) measured with an endoscopic laser Doppler flowmetry in 27 healthy volunteers. They were randomly assigned to receive an endoscopic gastric submucosal injection (0.5 ml) of physiological saline (control group, N = 10), 50 micrograms of dopamine (DA) hydrochloride (N = 8), and 500 micrograms of a DA antagonist, metoclopramide (MCP) (N = 9). The drugs were dissolved in the same saline volume (0.5 ml) as used in control group and were injected via the mucosal area where the baseline GMBF was measured and the postdose GMBF was monitored until 5 min postdose. There was no significant difference in the mean (+/- SEM) baseline laser Doppler signals among the control, DA, and MCP groups (92.6 +/- 9.3, 81.8 +/- 9.0 and 96.9 +/- 13.3 mV, respectively). In the control group, no significant postdose changes in the laser Doppler signals occurred until 5 min postinjection. In contrast, the DA group exhibited a significant (P < 0.05 or 0.01) increase in the laser Doppler signals at 2, 3, 4, and 5 min postdose (118.9 +/- 18.8, 128.5 +/- 16.9, 146.6 +/- 18.6, and 131.2 +/- 14.2 mV, respectively), whereas the MCP group exhibited a significant (P < 0.05 or 0.01) decrease in the signals at 4 and 5 min postdose (67.9 +/- 5.3 and 64.8 +/- 3.5 mV, respectively), as compared not only with the respective baseline values but also with those obtained from other two groups at the corresponding postinjection periods.(ABSTRACT TRUNCATED AT 250 WORDS)