PHOTOCONTROLLED RELEASE OF NICOTINE FROM RU(BPY)2NIC2 AND ITS EFFECT ON RAT TRACHEAL SMOOTH MUSCLE CONTRACTION

Background. Ru(bpy)₂Nic₂, a bipyridine ruthenium complex, is a light-sensitive compound capable of releasing nicotine upon irradiation with visible light (420–470 nm). Given its high quantum yield (φs = 0.23), it offers precise control over nicotine release, making it a valuable tool for investigating nicotinic acetylcholine receptor (nAChR) activation in biomedical research. Methods. High-performance liquid chromatography (HPLC) and tensometric analysis of rat tracheal smooth muscle contractions were used in this study. Results. Experimental findings demonstrated that Ru(bpy)₂Nic₂ induces a phasic-tonic contraction pattern in rat tracheal smooth muscle. The phasic phase is initiated by nicotine, while photolysis by-products activate P2X and P2Y purinergic receptors and stimulate prostaglandin release from the tracheal epithelium, thereby contributing to the sustained tonic component of contraction. Conclusions. Overall, Ru(bpy)₂Nic₂ provides an efficient and controllable nicotine source for biomedical research, with high photolysis efficiency and the ability to generate biologically relevant nicotine concentrations using accessible light sources.