Effect of paraquat on serum and lung angiotensin I converting enzyme (AICE) activity in beagle dogs.

The purpose of this study was to examine the relationship between lung or serum angiotensin I converting enzyme (AICE) activity and lung damage due to the administration of paraquat (PQ) which develops into PQ toxicity. Our experimental animals consisted of 19 beagle dogs (1-1.5 years old) that were allocated, randomly, into 2 treatment group, consisting of 11 PQ-treated animals and a control group of 8 saline-treated animals. These canines were administered PQ dichloride sc at a dose of 1.0 mg/kg body weight (PQ group) or sc saline at a dose of 0.5 ml/kg body weight (control group) for 7 to 11 consecutive days; these are doses which had been shown to be toxic to lungs. If a decrease in the animal's body weight was detected, the administration of PQ to that dog was discontinued. Body weight loss was observed in 10 of the 11 dogs treated with PQ. Representative dogs were sacrificed on days 11, 25 and 180 for the determination of both serum and lung AICE activity. The PQ group experienced a reduction in lung AICE activity and an elevation in the serum AICE activity. These results suggest that PQ damaged the endothelial cells of the lung and releasing lung AICE into the circulating blood, which led to an elevated total AICE activity in the serum. This pattern suggested damage to endothelial cells, indicating that PQ produced either continuing or repeated reinjury to lungs. Only the lungs were injured; therefore AICE from the rest of the body would not be expected to contribute to our AICE measurements.(ABSTRACT TRUNCATED AT 250 WORDS)