Effects of oral alcohol on superior mesenteric artery blood flow in normal man, horizontal and tilted.

1. The cardiovascular effects of oral alcohol (0.5 g/kg body weight diluted to 300 ml in sugar-free orange juice) were compared with those of placebo in 10 normal subjects. Measurements were made while the subjects were supine and horizontal for 45 min and after 10 min of 45 degrees head-up tilt. 2. After alcohol, plasma alcohol levels rose from 1.9 +/- 1.3 to 61.6 +/- 6.5 mg/100 ml. After placebo, plasma alcohol levels did not increase. After alcohol and placebo, supine blood pressure was unchanged; heart rate, both supine and during tilt, rose after alcohol only. 3. After alcohol, superior mesenteric artery and digital skin blood flow increased and calculated vascular resistances fell. There was no change after placebo. 4. Forearm blood flow, forearm vascular resistance and cardiac index did not change in either phase, except for a fall in cardiac index during tilt but only after alcohol. 5. In conclusion, the acute ingestion of 0.5 g of alcohol/kg body weight in normal subjects raised heart rate and actively dilated the superior mesenteric artery and digital skin vessels. There was no effect on blood pressure, cardiac output and skeletal muscle vascular tone. During head-up tilt after alcohol, there was a tendency for blood pressure to fall with a compensatory rise in heart rate.