Prevention by L(-) ascorbic acid of isoproterenol-induced cardiotoxicity in primary cultures of rat myocytes.

Primary cultures of rat myocytes were exposed to various doses of L-isoproterenol (ISO) for 4, 12 and 24 h. L-ascorbic acid (AA) was added to some cultures immediately after exposure to ISO to determine if antioxidants reduce the toxicity caused by ISO. Leakage of lactate dehydrogenase (LDH) and cell viability were used as indices of cell injury. A significant increase in LDH release was found 24 h after exposure to 1 X 10(-4) M ISO alone. Higher doses (5 X 10(-4) and 1 X 10(-3) M) caused significant enzyme release 4, 12 and 24 h after exposure. The viability of cultures exposed to toxic doses of ISO for 4 h was not affected. A dose-dependent decrease in cell viability was observed 12 h and 24 h after exposure to ISO. L-ascorbic acid (5 X 10(-3) and 1.5 X 10(-2) M) significantly reduced the LDH release caused by ISO. The enzyme release from cultures exposed to 5 X 10(-4) and 5 X 10(-3) M AA alone was similar to that of control cultures. However, 1.5 X 10(-2) and 3 X 10(-2) M AA caused marked LDH release. The viability of cultures subjected to ISO in the presence of 5 X 10(-3) M AA was similar to that of controls. Our results show that AA protects against the LDH release and decreased cellular viability caused by toxic doses of ISO.