RT Journal Article SR Electronic T1 Increase in plasma β endorphins precedes vasodepressor syncope JF British Heart Journal JO Heart FD BMJ Publishing Group Ltd and British Cardiovascular Society SP 596 OP 596 DO 10.1136/hrt.71.6.596-a VO 71 IS 6 YR 1994 UL http://heart.bmj.com/content/71/6/596.2.abstract AB