Vasoactive receptors in abdominal blood vessels of the dogfish shark, Squalus acanthias

Previous studies have demonstrated that the ventral aorta of the dogfish sh ark, Squalus acanthias, responds to a variety of cell-signaling agents. To investigate the generality of vasoactive receptors in the shark vasculature , in particular a conductance artery (anterior mesenteric) and vein (poster ior intestinal), I measured the effect of acetylcholine, endothelin, nitric oxide, natriuretic peptides, and prostaglandins on tension in isolated rin gs from these vessels. Both vessels responded to these agents, and response s to receptor-specific ligands for endothelin and natriuretic peptide recep tors suggest that B-type endothelin receptors are expressed in both vessels and that the artery expresses both A- and B-type natriuretic peptide recep tors; however, the vein (like the ventral aorta) expresses only the B-type natriuretic peptide receptor. My data suggest that a suite of signaling sys tems is ubiquitous in both arteries and veins in at least this elasmobranch species. Their role in hemodynamics and osmoregulation (perfusion of gill and rectal gland) remains to be determined.