The Journal of Laryngology & Otology July 2002, Vol. 116, pp. 536–538 Effect of Ringer-Lactate and isotonic saline solutions on mucociliary clearance of tracheal epithelium: an experimental study in rats Murat U ¨ nal, Hakki Oktay Seymen * Abstract Isotonic saline solution is frequently used in nasal and tracheal lavage. In a previous clinical study, it was found that Ringer-Lactate solution, as a nasal lavage, was better for mucociliary clearance function than isotonic saline solution after nasal septal surgery. In this experimental study, the effects of Ringer-Lactate and isotonic saline solutions on mucociliary clearance of healthy rat tracheal epithelium were investigated by measuring the transport of carbon particles. We found that tracheal segments that were irrigated with Ringer-Lactate had better mucociliary transport than those irrigated with isotonic saline (p = 0.035). Key words: Nasal Lavage Fluid; Mucociliary Clearance; Carbon Introduction Mucociliary clearance is a physiological process that provides a ow of mucus over ciliated epithelial cells. It is the rst defensive barrier against potentially harmful biological and physical particles with a diameter between 0.5 to 5 m m in both the upper and lower respiratory tract. Mucociliary clearance depends on the number of cilia, the frequency of the ciliary beat, whether they are synchronous and the quality and viscoelastic properties of the mucus. 1 The physiological factors controlling mucociliary clearance are largely unknown but even in the absence of neural control it is well preserved. 2 Endonasal irrigation has frequently been recom- mended in the treatment of patients with acute and chronic rhinosinusitis and in the post-operative care of patients who have undergone nasal or sinus surgery. Isotonic saline is one of the most frequently used solutions for nasal lavage. Our previous clinical study has demonstrated that Ringer-Lactate solution is better for mucociliary clearance than isotonic saline solution after nasal septal surgery. 3 The aim of this experimental study was also to compare the effects of these two solutions of the mucociliary clearance in healthy rat tracheal epithelium. Materials and methods The study was approved by the Animal Research Committee of the Cerrahpasa School of Medicine Istanbul University and the animals received care in compliance with ‘The Principles of Laboratory Animal Care’ formulated by the National Society for Medical Research and the ‘Guide for the Care and Use of Laboratory Animals’ prepared by the National Academy of Sciences. Fifteen Wistar- Albino type female rats, weighing 180 to 230 g, were observed for ve days at the animal care laboratory to exclude any underlying diseases. Experimental design After anaesthesia with keta- mine hydrochloride 40 mg/kg intraperitoneally, a vertical neck incision was made. The trachea was exposed by blunt scissor dissection, and a 1 cm in length cervical tracheal segment was excised. Each animal was decapitated immediately. This C-shaped tracheal segment was divided longitudinally into two equal pieces by microsurgery in order to avoid any damage to the epithelium. After marking the lower part of each piece, one of them was irrigated with Ringer-Lactate solution (Group A) and the other was irrigated with isotonic saline solution (Group B) for three minutes and then the respiratory epithe- lium was carefully dried. These surgically divided identical tracheal segments were washed with only one type of solution. The pieces of trachea were put into paraf n- lled smooth surfaced plates. Then carbon particles that had been prepared from an active carbon preparation (Eucarbon™ ) by crushing were placed on the lower parts of each piece (mucociliary activity in trachea is upward). In order to standardize the procedure, carbon particles that had 100 m m diameter was used. The size of particles was determined under a dissection microscope (Carl Zeiss Co., Germany) that provides a three dimen- From the Department of Otorhinolaryngology Head and Neck Surgery, School of Medicine, Mersin University, Mersin and the Department of Physiology * , Cerrahpasa School of Medicine, Istanbul University, Istanbul, Turkey. Accepted for publication: 19 February 2002. 536