Key result
Ioxaglate induced a biphasic mechanical response while iohexol only increased contractile force, though both increased resting membrane potential and decreased the effective refractory period.
Why the study?
What are the direct electromechanical effects of ioxaglate and iohexol on isolated rat atria?
What are the direct electromechanical effects of ioxaglate and iohexol on isolated rat atria?
Ioxaglate and iohexol exert direct electromechanical effects on rat atria that may explain the haemodynamic and ECG changes observed during coronary arteriography.
May underlie hemodynamic/ECG changes during arteriography; leaves open human relevance and contrast selection.
This study aimed at investigating the direct effects of two low osmolality radiographic contrast media, iohexol (non-ionic) and ioxaglate (ionic), on transmembrane action potentials, contractile force and refractoriness of isolated rat atrial preparations. Superfused with 10% solution, ioxaglate induced a biphasic mechanical response, initially decreasing and thereafter increasing contractile force. The same concentration of iohexol only increased contractile force. The two contrast media increased the resting membrane potential, action potential amplitude and rate of depolarization to the same extent. Iohexol prolonged repolarization. Both contrast media decreased the effective refractory period. The direct effects of contrast media on myocardial contractility in this study can explain the different haemodynamic effects of iohexol and ioxaglate in vivo. The observed effects on the action potentials in vitro can explain commonly observed ECG changes during coronary arteriography. The changes in depolarization, repolarization and refractoriness are probably related to the arrhythmogenic properties of these contrast media.
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Tande et al. (1990) studied this question. Iohexol and ioxaglate was evaluated on Transmembrane action potentials, contractile force and refractoriness. Ioxaglate induced a biphasic mechanical response while iohexol only increased contractile force, though both increased resting membrane potential and decreased the effective refractory period.
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