AJP - Heart and Circulatory Physiology, Vol 249, Issue 1 150-H154, Copyright © 1985 by American Physiological Society
Polarographic measurement of ascorbate washout in isolated perfused rabbit hearts
T. Arts, J. T. Kuikka, R. S. Reneman and J. B. Bassingthwaighte
To study the myocardial washout of ascorbate, the applicability of
polarographic detection of ascorbate ions by a platinum electrode
(sensitive area 0.03 mm2) was investigated, in both a calibration setup
(sampling flow along the electrode: 100 microliter X s-1) and isolated,
retrogradely perfused rabbit hearts. In the calibration setup at pH 7.4,
the sensitivity of the electrode was 70 microA/mol. This sensitivity
increased moderately with increasing pH (13%/unit pH) and increasing
sampling flow rate (14% at an increase from 100 to 150 microliter X s-1).
In the isolated hearts, ascorbate infused into the aorta was detected in a
right ventricular drain by the electrode as well as by the use of
14C-labeled ascorbate. Both recorded time courses were similar except for a
scaling factor dependent on flow velocity. During continuous infusion the
arteriovenous difference of ascorbate was 2 +/- 2% (SD), indicating a
relatively low consumption of ascorbate by the isolated heart. We conclude
that polarographic measurement of ascorbate in the coronary effluent of an
isolated rabbit heart can be performed on-line and relatively easily.
