[Extrarenal effects of furosemide on normal and ischemic cerebral tissue in the rat].

INTRODUCTION

Recent studies suggest that furosemide (FUR), a chloride cotransporting antagonist, acts directly on neurons of central nervous system modifying the ionic flow.

OBJECTIVE

The aim of the present study was to determine the extrarenal antiedema effect of FUR.

MATERIAL AND

METHODS

Male Sprague-Dawley rats were anesthetized with tiobarbital (60 mg/kg-1 ip), bilaterally nephrectomized and perfunded iv with solution of Ringer (RIN) (n= 5) or FUR (40 mg/kg-1) (n= 6), in equivalent volumes. The diuretic effect of FUR was excluded by bilateral nephrectomy. Two tungsten microelectrodes implanted on the cerebral cortex, registered the tissue impedance by the voltage fall of a square wave electric pulse (100 mA, 10 ms) tested every 120 seconds, before and after infusion of FUR or RIN and during global cerebral ischemia by D-tubocurarine induced respiratory arrest.

RESULTS

Preischemic FUR infusion induced a significant increase of voltage (t= 15.68; p< 0.0001). During global cerebral ischemia, the voltage fall was significantly lower in FUR than for RIN infusion (Wilcoxon Z= 3.9; p< 0.00001).

CONCLUSION

These results suggest that FUR reduced significantly the cerebral impedance i.e. antiedema effect, by an extrarenal action, under both basal and ischemia conditions.