Vasoactivity of the ventral aorta of the American eel (Anguilla rostrata),Atlantic hagfish (Myxine glutinosa), and sea lamprey (Petromyzon marinus)

To determine if vascular smooth muscle from teleost and agnathan fishes exp resses receptors for signaling agents that are important in vascular tensio n in other vertebrates, we exposed rings of aortic vascular smooth muscle f rom the eel (Anguilla rostrata), the hagfish (Myxine glutinosa), and the la mprey (Petromyzon marinus) to a suite of putative agonists, including: acet ylcholine, endothelin, nitric oxide, natriuretic peptides, and prostanoids. Acetylcholine constricted aortic rings from the eel, but had no effect on the rings from lamprey. On the other hand, endothelin constricted rings fro m all three species. Use of receptor-specific ET agonists demonstrated that only ETA receptors are expressed in the eel and lamprey aorta. The nitric oxide donor sodium nitroprusside or nitric oxide itself dilated rings from the eel, but both agonists constricted rings from the hagfish and NO produc ed a biphasic response (constriction followed by dilation) in the lamprey. Two natriuretic peptides, eel ANP and porcine CNP, produced marginally sign ificant dilation in the eel aorta, human ANP dilated the hagfish rings, and pCNP and eANP dilated the lamprey rings. The prostanoids PGE(1) and PGE(2) both dilated the eel aortic rings, and PGE(1) and carbaprostacydin (stable PGI(2) agonist) dilated the hagfish and lamprey rings. Our results suggest that receptors for a variety of vasoactive signaling agents are expressed in the aortic smooth muscle of the earliest vertebrates (lamprey and hagfis h), as well as the more advanced teleosts (eel). J. Exp. Zool. 289:273-284, 2001. (C) 2001 Wiley-Liss, Inc.