Particle deposition in the lung of the Göttingen minipig

Abstract

We report on particle deposition in the tracheobronchial and pulmonary regions of the respiratory tract of the minipig and its dependence on particle size. Four animals breathing spontaneously via the nose were exposed for 1 h to known concentrations of three different polydisperse dry aerosols composed of bovine serum albumin (BSA) and an oxide of a rare earth element: Y₂O₃, Sm₂O₃, and Er₂O₃. The mass size distributions of the rare earth elements of the three test aerosols have mass median aerodynamic diameters of 0.9, 2.5, and, 4.3 µm, and geometric standard deviations of σ_g = 2.0, 1.8, and, 1.7. The extrathoracic, tracheobronchial, and pulmonary regions of the respiratory tract were dissected, separately lyophilized, and chemically digested by microwave-assisted high pressure digestion. The tracer element in each compartment was determined by inductively coupled plasma mass spectrometry. A mass balance equation relating the tracer mass found in the lung compartments to the tracer mass inhaled was solved by linear regression to obtain the deposition fraction as function of particle sizes for the tracheobronchial and the pulmonary lung region. Estimated values for the respiratory minute volume were used in this context. For coarse particles >6 µm, the deposition fraction is <5% for both compartments. The deposition fraction for particles with aerodynamic diameter of ~3 µm is 21% in the tracheobronchial airways and 40% in the pulmonary airways.

Keywords::

• Lung deposition
• particle
• minipig

Acknowledgement

Provision of minipigs from Ellegaard Göttingen Minipig A/S, Dalmose, Denmark is gratefully acknowledged.

Declaration of interest

No external funding was received for this study. The authors declare no conflict of interest.