| In this paper, on the base of preincubation, using established precision-cut rat liver slices (PLCS) we investigated the effect of HAP on rat liver slices and the phagocytic activity of peritoneal exudates cells (PECs).1. The effects of preincubation on precision-cut rat liver slicesAfter preparation, slices were divided into two groups: the non-preincubation group and the preincubation group. The slices were usually incubated for 0, 0.5, 2, 4 and 6 h (time 0 h, which is taken as the control value, represents slices incubated in RPMI- 1640 for 5 min; time 0.5 h in the preincubation group represents slices incubated for 0.5 h after preincubation). MTT reduction was used to determine the survival of liver slices; GPT, GOT and LDH activity in slices were measured to reflect the toxicity to slices; .the metabolic functions were studied by determination of Na+-K+-ATP activity; the change of antioxidation was evaluated by GST activity.Incubation of slices in the non-preincubation group caused a significant (P<0.05) time-dependent reduction in GPT and GOT activity, and Na+-K+-ATP activity after 6 h. the lose of MTT reduction in the preincubation group followed a similar pattern, but the incubation stabilized at a significantly initial level in other criteria after 1 h of preincubation. And there was a similarity in MTT reduction, LDH and GST activity in the two groups within 6 h of incubation. The results showed that especially for long-term investigation, preincubation could limit mechanical injury and maintain slices' viability and useful lifespan.2. The effects of HAP on precision-cut rat liver slicesAfter 1 h preincubation, slices were incubated with either 0.7 or 1.4 mmol'L"1 HAP, which are the most optimal and highest doses for inhibiting hepatocellular carcinoma in vitro respectively, or RPMI-1640 without HAP for 1, 3, 5 and 7 h. MTT reduction was used to determine the survival of liver slices; GPT , GOT leakage (% of total activity) and LDH released in the medium were measured to reflect the toxicity to slices; the metabolic functions were studied by determination of Na+-K+-ATP activity and protein, glycogen content; the change of antioxidation was evaluated by GST activity. Compared with the control, exposure of slices to HAP at different concentration(0.7 and 1.4 mmol'L"1) in RPMI-1640 for 7 hr showed no obvious differences in criteria above, except that the GST levels of slices increased 88%(P<0.01) and 25% , 71%(P<0.01) and 29%(P<0.05) , -57%(P<0.05)and 86%(P<0.01) higher than that of control, respectively at 3, 5 and 7 hr. It is suggested that in short period of time, there is no obvious noxiousness and no obvious dose-dependent effects of HAP to liver slices.3. The effects of HAP on peritoneal exudates cellsThe phagocytic activity of PECs harvested from peritoneal of mice after a single intraperitoneal(i.p.) treatment with HAP was investigated in an in vitro phagocytic: phagocytic index(percentage of PECs ingested more than 3 fowl erymrocytes) and ingestion capacity(number of erythrocytes ingested per cell) were the parameters used for evaluation of the phagocytic activity. Compared with the control, statistically significant decreases of the phagocytic index (P<0.05) and of the ingestion capacity(P<0.05) of PECs were observed 3 and 18 hr after the treatment, and then recover their phagocytic function at 72 hr. Moreover, there were significant increases only in ingestion capacity 120h after the injection of mice (P<0.05). it is suggested that HAP could impede temporarily the phagocytic function and the alternations observed were in some sense time-dependent, but not dose-dependent.Conclusion1. Preincubation could limit slices' mechanical injury and maintain their viability and useful lifespan for long-term investigation.2. In short period of time, there is no obvious noxiousness and no obvious dose-dependent effects of HAP to liver slices.3. HAP could impede temporarily the phagocytic function and the changes observed were in some sense time-dependent, but not dose-dependent.
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