Effects of contrast media on cultured myocardial cells

To quantify and characterize mechanisms of negative inotropic effects of ionic and nonionic angiographic contrast media, spontaneously contracting monolayers of cultured chick ventricular cells were studied using the Renografin-76 and iohexol as characteristic ionic and nonionic contrast agents. Utilizing microscopic video-motion detector techniques the effect of each contrast agent on contraction amplitude was measured. Also, the effect of changes in the ionized calcium concentration and osmolality induced by the contrast agents was evaluated. The study demonstrated a linear depression of contractility by increasing contrast concentrations. The negative inotropic effect of Renografin-76 was significantly greater than that of iohexol. Renografin-76 demonstrated significant calcium binding, whereas iohexol had none. Correction for calcium binding by Renografin-76 partially reversed the negative inotropic effect of this agent. Hypertonic sugar solutions of equivalent osmolality to the contrast agents demonstrated dose-related negative inotropic effects such that, in this preparation, calcium binding by Renografin-76 and its high osmolality accounted for all its negative inotropic effect. In contrast, iohexol demonstrated an intrinsic negative inotropic effect not completely explained by its osmolality.