A Pleural Effusion Model in Rats by Intratracheal Instillation of Polyacrylate/Nanosilica

This method can provide insight into the toxicity of nanomaterials and can be applied for the study of pulmonary toxicity. This technique was derived to study the effects of polyacrylate/nanosilica-induced pleural effusion. Before beginning the instillation, sonicate a fresh, 10-milliliter, polyacrylate/nanosilica suspension in normal saline for 20 to 30 minutes, followed by 10 minutes of vortexing, before diluting the suspension to 3.125, 6.25, and 12.5 milligram per milliliter concentrations.

Next, confirm a lack of response to toe pinch in an anesthetized rat, and fix the front teeth of the animal to the board with a piece of nylon string. Using forceps and a frontal lets, gently open the mouth to visualize the fissure of glottis, and insert a fine tube into the bilateral bronchus. Then, instill 0.5 milliliters of the polyacrylate/nanosilica particles through the tube into the lungs, and place the rat in the supine position with monitoring until full recovery.

On days one, three, seven, and 14 after instillation, use an electric shaver to remove the hair from the chest and upper abdomen of each anesthetized rat, and place the rat on the mounting plate of an ultrasound system with a linear array transducer in the supine position. Apply ultrasound gel to the exposed skin, and place the transducer on the intercostal space and subcostal area to detect the pleural fluid. In order to detect the effusion accurately, select the left and right lateral positions to perform an ultrasound examination.

On day seven, both pleural effusion and pericardial effusion are detected in the 6.25 milligram per kilogram per milliliter instilled group. On day seven and 14, CT chest scans of the 12.5 milligram per kilogram per milliliter instilled animals are abnormal at the blunt posterior costophrenic angle, hinting at a small amount of pleural effusion. Transmission electron microscopy of pleural effusion samples reveals nanosilica nanoparticles individually and in clusters with a morphology consistent with that observed for nanoparticles within the prepared suspension.

The most important thing is to remember to visualize the fissure of the glottis and to insert a fine tube into the bilateral bronchus. The nanoparticles can also be instilled by inhalation or intravenous injection, as both methods have been performed in previous studies. This technique is useful for studying the development of pleural effusion.