The toxic effects on cardiac myocytes of tyledoside F, a cumulative neurotoxic cardiac glycoside isolated from Tylecodon grandiflorus
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Date
Authors
Van Rooyen, J.M.
Van der Walt, J.J.
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Published by the Government Printer, Pretoria.
Abstract
To investigate the cardiac cellular effects of tyledoside F, a cumulative neurotoxic bufadienolide and ouabain, a non-cumulative cardenolide, the whole-cell clamp method was used to measure the Na-K pump current after the Na-K pump had been activated by high intracellular Na²⁺. The toxic effects of tyledoside F and ouabain on cardiac myocytes were also investigated by observing the effect of the Ca²⁺ overload on the viability of myocytes during a period of 75 min.
From the results it is clear that there are similarities in the direct effects of tyledoside F and ouabain on the Na-K pump. It was found that ouabain inhibited the Na-K pump current more than that of tyledoside F. With regard to Ca²⁺ overload, there are differences in their mode of production of Ca²⁺ overload because cinnarizine protects the myocytes against ouabain-induced Ca²⁺ overload but not against tyledoside-induced Ca²⁺ overload. This study shows that with the whole-cell clamp technique tyledoside F inhibited the Na-K pump in a manner similar to inhibition of the pump by ouabain. Viability studies with myocytes indicated that tyledoside F also has other effects which are different from these of ouabain.
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Keywords
Veterinary medicine
Sustainable Development Goals
Citation
Van Rooyen, JM & Van der Walt, JJ 1990, 'The toxic effects on cardiac myocytes of tyledoside F, a cumulative neurotoxic cardiac glycoside isolated from Tylecodon grandiflorus’, Onderstepoort Journal of Veterinary Research, vol. 57, no. 4, pp. 223-227.