Stomach distension increases efferent muscle sympathetic nerve activity and blood pressure in healthy humans

Although the enteric nervous system is usually described as a separate and independent entity, animal studies show that gastric distension causes a re flex increase in arterial pressure and a sympathetically mediated increase in heart rate and peripheral vascular resistance. To assess the influence o f gastric distension on sympathetic outflow and blood pressure, we recorded muscle sympathetic nerve activity (MSNA) from the peroneal nerve by micron eurography in eight healthy volunteers. The stomach was distended by means of a barostat, using a single staircase protocol by which pressure was incr eased by 2 mmHg every 3 min. Gastric sensory function was assessed at each distension step by using a visual analog scale (VAS) for sensations of full ness, nausea and pain. For comparison, we also performed a cold presser tes t. The MSNA increased on barostat-induced gastric distension with an almost concomitant elevation of blood pressure. The increase in both was proporti onal to the intragastric pressure and both decreased towards initial values after the end of distension. Heart rate increased inconsistently and only at higher distension pressures that were associated with high VAS scores. T he opposite was found for the cold presser test. The results of this study confirm the existence of a functional relationship between gastrointestinal distension and cardiovascular function. Decrease in this gastrovascular re sponse may play a role in postprandial hypotension in the elderly, since th e MSNA responses to simulated microgravity decrease with age. (C) 1998 Else vier Science B.V. All rights reserved.