[In vitro killing of adult Trichinella spiralis by exogenous nitric oxide].

OBJECTIVE

To investigate the lethal effect of exogenous nitric oxide on adult worms of Trichinella spiralis in vitro.

METHODS

Adult worms of T. spiralis isolated from the small intestine of Trichinella-infected BALB/c mice were cultured in RPMI 1640 medium with sodium nitroprusside (SNP) in different final concentration of 0, 0.02, 0.05, 0.10, 0.20, 0.50, and 1.00 mmol/L, 1.00 mmol/L SNP+0.15 mmol/L hemoglobin (Hb), 1.00 mmol/L SNP+0.15 mmol/L FeSO4, 1.00 mmol/L SNP+1.00 mmol/L L-cysteine (L-cyst), 1.00 mmol/L SNP+0.15 mmol/L FeSO4 +1.00 mmol/L L-cyst, respectively, and incubated at 37 degrees C in a humidified 5% CO2 atmosphere. On the 4th day after incubation, the adult worms were stained with safranin, and observed under light microscope. The worm mortality in the groups was analyzed.

RESULTS

Under concentration of 0.02 and 0.05 mmol/L, SNP was not cytotoxic to adult T. spiralis with an inhibition of (1.4 +/- 1.2)% and (3.2 +/- 1.0)%, respectively. The worm mortality in the groups of SNP 0.10, 0.20, 0.50, and 1.00 mmol/L was (9.9 +/- 1.8)%, (37.7 +/- 2.5)%, (50.1 +/- 3.5)%, and (80.8 +/- 1.1)%, respectively, significantly higher than that of negative control group [(1.9 +/- 0.2)%, P < 0.05]. There was a positive linear correlation between the worm mortality and SNP concentration in the range of 0.02-1.00 mmol/L. Combination of hemoglobin, L-cyst, FeSO4 and FeSO4+L-cyst with 1.00 mmol/L SNP led to a decrease of the mortality from (80.8 +/- 1.1)% to (56.5 +/- 3.7)%, (69.8 +/- 2.3)%, (74.8 +/- 2.4)%, (72.7 +/- 5.6)%, respectively.

CONCLUSION

Exogenous nitric oxide released from SNP can kill adult worms of Trichinella spiralis. However, hemoglobin and L-cysteine+FeSO4 can reverse its lethal effect on the parasites.