Vasoconstriction by angiographic contrast media in isolated canine arteries

The article by Gomi (1992) reports a vasoconstrictor response to high osmolar contest media (HOCM) in canine arterial strips in vitro. In vivo, HOCM are generally understood to be net vasodilators (Steiner et al, 1980). The evidence presented by Gomi therefore supported an indirect (neural or humoral) mechanism for the dilator event. However, the authors state in their discussion that “we were unable to find any reports studying vasodilation caused by CM based on in vitro vascular preparations”. We have recently demonstrated vasodilation resulting from an infusion of iothalamate in the isolated rat kidney, constriction only being observed when the CM infusion was stopped (Hayloretal, 1991).