Is Nitric Oxide or a Prostaglandin the Endothelium-Derived Relaxing Factor in Fishes?

脊椎动物的血管有一层薄薄的细胞衬里，称为内皮，通常认为它只是提供一些保护，防止血细胞(红细胞、血小板等)粘连。至血管壁上的内皮下的血管平滑肌。然而，近年来，很明显，内皮细胞产生各种化学信使，这些信使不仅可以防止血液凝结，还可以通过刺激血管平滑肌的收缩或松弛来控制血管本身的直径。其中最著名的是所谓的“内皮细胞衍生的松弛因子”，它被认为不是一氧化氮。这种气体现在被认为是哺乳动物的主要EDRF，尽管内皮细胞会产生其他扩张物质，如前列腺素PGI2和PGE。埃文斯博士的初步证据表明，在角鲨等早期脊椎动物中，情况可能并非如此。在该物种中，内皮一氧化氮系统似乎缺失，而PGE，而不是PGI2，似乎是唯一的EDRF。PI感兴趣的是描绘EDRF控制系统的演变，确定它出现的对象以及它在不同鱼类群体的心血管控制中扮演的角色。NSF的这一奖项将允许他做出这些决定。

Blood vessels in vertebrates have a thin lining of cells termed the endothelium, which was generally thought to provide little more than some protection against the adhesion of blood cells (RBCs, platelets, etc.) to the vascular smooth muscle which underlies the endothelium on the vessel wall. However, in recent years, it has become apparent that endothelial cells produce a variety of chemical messengers that no only protect against blood clotting but also control the diameter of the vessel itself by stimulating contraction or relaxation of the vascular smooth muscle. The most famous of these is the so-called "endothelium-derived relaxing factor", which is not thought to be nitric oxide. This gas is now considered to be the dominant EDRF in mammals, despite the fact that the endothelial cells produce other dilatory substances, such as the prostaglandins PGI2 and PGE. Dr. Evans' preliminary evidence has shown that this may not be the case in early vertebrates such as the dogfish shark. In this species, the endothelial nitric oxide system appears to be absent, and PGE, not PGI2, appears to be the only EDRF. The PI is interested in delineating the evolution of the EDRF control system, determining which it appeared and what role it plays in cardiovascular control in various groups of fishes. This NSF award will allow him to make these determinations.