Methylmethacrylate monomer (MN) bone cement is commonly employed in orthopedic procedures, particularly total hip and knee replacement, to anchor prosthetic devices to bone. Numerous cardiopulmonary complications can occur just after injection of MN. And MN produces direct relaxation of vascular smooth muscle in vitro. The purpose of this study was to determine if MN could have relaxation effect in tracheal smooth muscle too.

Each ring of rat trachea was suspended on wire supports in a bath with Tris Tyrode solution. Dose response curves of MN were recorded after contraction of tracheal ring with acethylcholine (Ach) 10^-5 M or cabachol (Cch) 10^-8 M. MN was administered in denuded tracheal rings and compared it's effect with intact tracheal rings to see the effect of epithelium for contraction. And MN dose response curves were recorded after pretreatment of nitric oxide synthase inactivator (L-NAME), muscarinic receptor blocker (atropine), beta-adrenaline receptor blocker (propranolol), adenylyl cyclase inhibitor (SQ22536) respectively. The effects of MN on cellular Ca²⁺ and K⁺ migration in rat tracheal preparations were studied.

MN significantly inhibited acetylcholine or carbachol induced contractions of tracheal rings dose-dependently (P < 0.05). This relaxation effect of MN was not recovered in denuded tracheal rings. And pretreatment with L-NAME, propranolol, atropine, SQ22536 or tetraethylammonium respectively did not recover the relaxation effect of MN. MN inhibited both intracellular calcium release and extracelluar calcium influx.

The relaxation effects of MN on rat tracheal rings are not related with epithelium, nitric oxide, muscarinic, or beta-adrenergic receptor. Methylmethacrylate monomer inhibits both intracellular calcium release and extracelluar calcium influx.