Comparative cytotoxic responses of cultured avian and rodent aortic smooth muscle cells to allylamine

The present studies were designed to compare the acute cytotoxic responses of cultured avian and rodent aortic smooth muscle cells (SMCs) to allylamine (AAM), a selective vascular toxin. SMCs were isolated from male Japanese quail or Sprague-Dawley rats and established in culture by standard procedures. Cellular glutathione (CSH) content and lactate dehydrogenase (LDH) leakage were used as indices of cytotoxicity. Exposure of avian and rodent SMCs in primary culture to AAM (0.2-200 μM) for 4 h was associated with a significant reduction in cellular CSH and enzyme leakage in cultures of both cell types. Increased exposure time to 24 h further depleted cellular CSH levels and enhanced the leakage of LDH in primary cultures of avian SMCs. In contrast, enhanced LDH leakage occurred without further CSH depletion in primary cultures of rodent SMCs upon exposure to AAM for 24 h. Removal of serum did not modulate the cytotoxic response profile of primary cultures of avian SMCs treated with 200 μM AAM, but was associated with marked elevation in cellular CSH levels and significant LDH leakage in rodent SMC cultures. The cytotoxic responses to 0.2-200 μM AAM in secondary cultures of avian SMCs were comparable to those observed in primary culture. In contrast, AAM-induced enzyme leakage did not consistently correlate with changes in CSH content in subcultured rodent SMCs. Challenge with 200 μM acrolein (ACR) for 4 h reduced the CSH content in avian, but not rodent, subcultures of SMCs. However, significant LDH leakage occurred in subcultures of both cell types upon exposure to ACR. Although hydrogen peroxide (H₂0₂) did not modulate CSH levels in avian or rodent cultures, leakage of LDH was observed in rat SMCs challenged with 200 μM H₂0₂. Removal of serum did not alter the cytotoxic responses of avian subcultures to 200 μM AAM for 24 h, but fully prevented cytotoxicity in rodent subcultures. These data suggest that potentially significant variations in the sequence of events leading to injury may exist between quail and rat aortic SMCs. These differences may contribute to the enhanced avian susceptibility to AAM- induced aortic injury in vivo.