Effect of paraquat on lung calcium transport

The effect of paraquat on lung subcellular calcium transport was studied in male Sprague-Dawley rats. With a high dose of 30 mg/kg given i.p., a significant decrease in the lung mitochondrial and microsomal calcium uptake at 24, 48, and 72 h after paraquat was observed. Trend of recovery was evident at 96 h in the surviving rats. The lung water content and thymidine incorporation into the lung DNA increased significantly after 72 h and 48 h of paraquat administration, respectively. Groups of animals also received a lower dose of paraquat at 10 mg/kg i.p. and were sacrificed at 1, 2, 3, 4, 6, and 8 days. Continuous decrease in the mitochondrial and the microsomal calcium uptake until 4 days followed by a trend of recovery were observed. Thymidine incorporation into the lung DNA increased significantly at all the time periods after day 3 but no significant increases were observed in the lung water content at this dose. The results indicate that paraquat significantly disrupts the lung intracellular calcium uptake even at the doses which do not show any significant increase in the lung water content.