The effect of second hand cigarette smoke exposure on the rodent alveolar type IIB sodium-phosphate cotransporter

Abstract

The sodium-phosphate (NaPi) type IIb cotransporter protein is expressed on the apical membrane of type II alveolar cells in the lung and is likely involved in surfactant synthesis. Several studies have demonstrated an inhibition of surfactant secretion in the lung after cigarette smoke exposure. The aim of this study was to test the hypothesis that second-hand cigarette smoke (SSCS) exposure decreases NaPi-IIb cotransporter expression in the mouse lung. We exposed mice to SSCS for 14 days using a nose-only exposure column connected to a vacuum. Cotinine levels in the urine were assayed (7.75 fold greater level in smoke group). We developed polyclonal antibodies against the N-terminus of the NaPi-IIb peptide. Northern and Western blots were performed with the animals' lung tissue. We observed ~60% reduction in NaPi-IIb mRNA expression and ~20% reduction in NaPi-IIb protein expression in mice. We concluded that SSCS exposure reduced the expression of the NaPi-IIb cotransporter.