GI motor inhibition associated with acute exposure to methyl methacrylate vapor

A mixture of monomeric methyl methacrylate vapor in air was delivered into the breathing air of chloralose-urethan anesthetized dogs. Fixed length exposures to 2000-ppm doses of the vapor resulted in a transient drop in arterial blood pressure and a marked inhibition of ongoing GI motor activities. Motor inhibition always continued for a variable time (approximately 10-15 min) subsequent to the cessation of methyl methacrylate vapor administration. This inhibitory response was not blocked by bilateral vagotomy, spinal transection, splanchnectomy, or the intravenous administration of tetraethylammonium chloride. Another series of experiments determined that the administration of blood from a dog receiving methyl methacrylate vapor produced GI motor inhibition in another dog not connected to the experimental gas mixture. Therefore, it is concluded that, aside from any reflex effects produced, methyl methacrylate vapor in sufficient concentration probably exerts a direct inhibitory effect upon GI smooth muscle that is mediated by the cardiopulmonary systems.