Effects of diesel exhaust particles on blood pressure in rats

The effects of diesel exhaust particles (DEP) on pulmonary functions and co nsequent diseases are well known, but there have been few reports concernin g involvement of the cardiovascular system. In order to assess a direct act ion of DEP on cardiac tissue, the effects on blood pressure of intravenous administration of 12 or 120 mg/kg DEP to anesthetized rats were studied for a 15-min period. DEP (120 mg/kg) significantly lowered blood pressure for 25 s with no signs of arrhythmia or mortality, a phenomenon seen in guinea pigs. After 25 s blood pressure gradually returned to control levels and wa s maintained for 15 min. The 12-mg/kg DEP concentration did not markedly af fect rat blood pressure. Pretreatment with atropine (24 mg/kg) blocked the DEP-induced fall in blood pressure, while pretreatment with propranolol (48 mg/kg) proved ineffective against DEP, suggesting involvement of the paras ympathetic system. Data show that the rat is less sensitive to DEP-induced effects on blood pressure and may be a poor model to reflect cardiovascular changes.