Primary Studies Of Exogenous Nitric Oxide On Muscle Larvae Of Trichinella Spiralis In Vitro

Objective:To investigate the lethal effect of exogenous nitric oxide on muscle larvae of Trichinella spiralis in vitro cultivation through inducing apoptosis of muscle larval cells by exogenous nitric oxide. Method: Larvae of Trichinella spiralis were isolated from the muscle of a Trichinella-infected BALB/c mouse.The muscle larvae were cultured in RPMI-1640 medium with sodium nitroprusside(SNP) in different doses of 0.02, 0.05, 0.10, 0.20, 0.50, and 1.00mmol/L, respectively for 4 days at 37℃5%CO2 . Hb 0.15mmol/L, FeSO4 0.15mmol/L, L-cyst 1.00mmol/L were used as inhibitors. The effect on the viability of muscle larvae was observed on days 2, 3, and 4. The differences of inhibition ratio in the groups were compared on day 4. The apoptosis of muscle larval cells were detected by TUNEL assay, HE staining, TEM, and fluorescence microscopy. Results: Exogenous nitric oxide derived from SNP killed the muscle larvae of T. spiralis.The lethal effect of exogenous nitric oxide seemed to have concentration and time dependent. On the fourth day, no statistical significance was noted when the larvae were incubated with SNP at concentration of 0.02 mmol/L (P>0.05). Increase of concentration of SNP to 0.05, 0.10, 0.20, 0.50, 1.00mmol/L could improve the parasite killing when compared with control (P<0.05) . Addition of hemoglobin, L-cysteine, FeSO4 to SNP resulted in a decrease of the inhibition. Exogenous nitric oxide induced the apoptosis of muscle larval cells detected with TUNEL assay, TEM, and fluorescence microscopy. Conclusion: Exogenous nitric oxide had the lethal effect on muscle larvae of T. spiralis in vitro in dose dependent manner detected by TUNEL assay, TEM and fluorescence microscopy. Hb, FeSO4, L-cyst could inhibit the parasite killing with exogenous nitric oxide.