Key result
Beta-blocker pretreatment prevents isoprenaline-induced cardiac necrosis but fails to protect against established lesions.
Why the study?
The heart-damaging effect of isoprenaline and the antagonistic effect of β-adrenoreceptor blocking agents needed quantitative evaluation.
May guide beta-blocker testing in catecholamine rat models; leaves open human cardiotoxicity translation.
Histological methods show that low doses of (±)-isoprenaline may produce cardiac necroses in the rat. The percentage of animals with focal necroses was related to the dose within the range 0·005 to 0·5 mg/kg administered subcutaneously. Therefore the heart-damaging effect of isoprenaline as well as the antagonistic effect of β-adrenoreceptor blocking agents could be evaluated quantitatively. Pre-treatment of animals with dichloroisoprenaline, pronethalol and propranolol produced a parallel displacement to the right of the dose-response line for isoprenaline. However, when lesions were already in progress, these agents were without protecting effect.
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Dorigotti et al. (1969) studied Isoprenaline-induced cardiac necroses. β-adrenoreceptor blocking agents (dichloroisoprenaline, pronethalol, propranolol) vs. Isoprenaline alone was evaluated on Percentage of animals with focal necroses. Pre-treatment with β-adrenoreceptor blocking agents antagonized isoprenaline-induced cardiac necroses in rats, but offered no protection when lesions were already in progress.