Effects of Angiographic Contrast Media and Hypcrtonic Saline Solution on Cerebral Venous Outflow in Autoregulating Brains

Abstract

Meglumine iothalamate,sodium diatrizoate,meglumine diatrizoate and sodium acetrizoate contrast media were all shown to be cerebral vasodilators in autoregulating beds. The vasodilatory capacity of the agents tested and commonly used today in angiography was significant but of much less intensity than sodium acetrizoate (Urokon) which has been withdrawn from clinical use. Urokon abolishes autoregulation. In autoregulating brains cerebral vasodilation produced by contrast agents after intracarotid injection was similar to that which occurs with hypertonic saline solutions. The degree of vasodilation after intracarotid injections of hypertonic saline solution in autoregulating cerebrovascular beds is directly related to the concentration of the solutions. The mechanism for cerebrovascular responses to both contrast materials and hypertonic saline solutions appeared related to their osmolarity. To determine experimentally cerebrovascular activity of vasoactive agents, they should be evaluated in autoregulating cerebral circuits since this represents the normal physiologic state. Autoregulation persists in cerebrovascular beds which have been visualized with sodium diatrizoate, meglumine diatrizoate and meglumine iothalamate.