Archives of toxicology
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Archives of toxicology · Jan 2004
Use of M-mode and Doppler echocardiography to investigate the cardiotoxicity of minoxidil in beagle dogs.
Doppler and M-mode echocardiography (EC) were used to investigate the effects of minoxidil on the cardiac function of the dog and potentially to clarify the pathogenesis of cardiac lesions, in particular the necrotic lesion in the left ventricle and the haemorrhagic lesion in the right atrium. Groups of three dogs were treated with a single oral dose of 0.5 or 2 mg/kg minoxidil or control vehicle, and M-mode and Doppler parameters were recorded at different time points before as well as 1, 3 and 24 h after treatment. The treatment produced a number of changes in M-mode parameters that indicate an increase in left ventricle contractility, in particular, increases in the percentage of thickening of the left ventricle wall during systole and in ejection fraction, and decrease of systolic volume. ⋯ The fact that the change is more marked in the right than in the left atrium may explain why the lesion occurs only in the right atrium in dogs. This study showed, therefore, that Doppler EC associated with M-mode EC is a useful method for obtaining pertinent information on the pathogenesis of the left ventricle lesion induced by haemodynamic mechanisms. Moreover, Doppler EC allowed the assessment of changes in the function of the right atrium that may be involved in the development of the right atrial lesion.