Fura dextran, potassium salt, 10,000 MW, anionic is a derivative of the ratiometric, UV light—excitable fura-2 indicator (F-1200) coupled to a water-soluble 10,000 MW dextran. This dextran salt form is useful for intracellular loading by microinjection, infusion from patch pipette or uptake induced by our Influx pinocytic cell-loading reagent (I-14402). Fura dextran conjugates tend to remain in the cytosol without compartmentalization or leakage and are less likely to bind to cellular proteins, making them useful for long-term Ca2+ measurements.