Effects of 21-aminosteroids in neonatal rat cardiac myocyte cell cultures exposed to free radicals.

OBJECTIVE

The aim was to test a group of 21-aminosteroids, U74006F, U75412E, and U74500E, known as lazaroids, for their ability to prevent alterations in neonatal rat cardiac myocytes exposed to solutions containing a xanthine oxidase mediated free radical generating system.

METHODS

Myocytes were either left untreated (non-treated cultures) or pretreated for 15 min with the drug vehicle or one of the lazaroids. Myocytes were either examined as non-exposed control cultures or exposed to the free radical generating system for 60 min. Measurement of [3H]arachidonate label in a lipid extract of the culture medium and release of lactate dehydrogenase (LDH) into the medium were analysed.

RESULTS

Myocytes not treated with lazaroids and vehicle treated myocytes exposed to free radicals showed a significant release of [3H]arachidonate and lactate dehydrogenase (LDH). At a dose 1 x 10(-5) M, all lazaroid treated myocytes showed significantly lower release of [3H]arachidonate measured in the total lipid extract compared to the non-treated or vehicle treated cultures. Release of [3H]arachidonate was significantly lower for the myocytes treated with U74006F and U74500E at 1 x 10(-6) M concentration. Only the U74006F treated myocytes showed protection at 1 x 10(7) M. LDH release was significantly attenuated at a dose of 1 x 10(-5) M for the U75412E treated myocytes and at 1 x 10(-5) and 1 x 10(-6) M for the U74500E treated myocytes compared to the myocytes not pretreated with a lazaroid and exposed to free radicals.

CONCLUSIONS

Lazaroids provide protection against the release of [3H]arachidonate and LDH from myocardial cells exposed to free radical mediated injury. U74006F appeared to have the higher efficacy, at equal molar concentrations, in protecting against the release of [3H]arachidonate, whereas U74500E was observed to have the higher potency in inhibiting LDH release.