Summary of symposium on cerebral blood flow: effect of nerves and neurotransmitters. Cardiovascular Center, University of Iowa, Iowa City, Iowa, June 16--18, 1981.

In 1977 the first comprehensive symposium about neural regulation of cerebral blood flow was held in Stockholm. The symposium, which was organized by Drs. Christer Owman and Lars Edvinsson, was stimulating and provocative. It was essentially a workshop: new data were presented and controver­ sial problems and contradictory results were dis­ cussed at length (see Owman and Edvinsson, 1977). Dr. Melvin Marcus and I thought that it would be appropriate to bring together a number of active investigators in this area of research to reexamine in depth the cerebral vascular effects of nerves and neurotransmitters. There were several reasons to think that a symposium would be timely. First, there have been important recent advances in un­ derstanding cellular mechanisms of cerebral ves­ sels. Second, a systematic examination of cerebral vascular effects of neurotransmitters has led to a consensus in some areas. Third, recent evidence has resolved some of the controversy concerning effects of sympathetic nerves on cerebral vessels. Fourth, studies in vitro and in vivo concerning the role of vasodilator mechanisms have resulted in conflicting results, for reasons that are unclear. Fifth, the role of central neural pathways in the reg­ ulation of cerebral blood flow remains unsettled. The studies of central pathways, which are difficult and challenging, require careful examination and cautious interpretation. The symposium was planned by an organizing committee that was diverse in terms of area of interests and geography. The committee members were Drs. John Bevan, Murray Harper, Donald