THE EFFECT OF HYPERTONIC SODIUM-BICARBONATE ON QRS DURATION IN RATS POISONED WITH CHLOROQUINE

Objective: To determine efficacy of hypertonic sodium bicarbonate in n arrowing QRS prolongation produced by chloroquine. Design: Randomized, controlled animal experiment using an accepted rat model of sodium ch annel blockade. Methods: Hypotension and widening of QRS complexes (le ad II) of the ECG were produced in 16 rats by administration of a tota l of 87 mg/kg chloroquine intravenously over 20 minutes. Eight rats we re treated with 6 mL/kg 1 M sodium bicarbonate intravenously over two minutes beginning ten minutes into the chloroquine infusion. Serial me asurements of QRS duration and systolic blood pressure were obtained f or 30 minutes. Results: QRS intervals narrowed more rapidly in animals receiving sodium bicarbonate (p = .045), although the difference in m ean rate of narrowing between groups was modest at only .23 msec/min. Because of large variances, no statistically significant differences c ould be demonstrated in systolic blood pressure. Conclusions: Hyperton ic sodium bicarbonate partially reversed sodium channel blockade and r esultant QRS interval prolongation produced by chloroquine in rats. Th ese data should be interpreted with caution, given the need to extrapo late to humans and the modest effect of sodium bicarbonate on QRS narr owing.