Cardiac functions are controlled by higher brain centers and sympathetic and parasympathetic nervous sys­tems, which act via adrenergic and muscarinic receptors respectively, Cardiac baroreceptor, renal barore-ceptors and arterial baroreceptors in­fluence reflexly the activity of cardio­vascular autonomic nerves. The potent loop diuretic furosemide is used for rapid relief of acute pulmo­nary edema due to acute left sided heart failure and congestive heart fail­ure. So the present work was con­ducted to evaluate the effect of single intravenous dose of furosemide on cardiac autonomic activity in rabbits.
Seventy-two rabbits were random­ly divided into three equal major groups with different autonomic states; one with intact autonomic com­ponents, the second with blocked par­asympathetic components (0.2 mg/kg I.V. atropine), the third with blocked sympathetic (1 mg/kg I.V. atenolol). Each major group include four sub­groups; control (non furosemide treat­ed with intact kidneys; furosemide treated with intact kidneys; non furos­emide treated binephrectomized) and furosemide treated binep-hrecto-mized. Binephrectomized grou-ps al­low the assessment of furosemide au­tonomic activities independent of fu­rosemide renal effects. Our data demonstrate modulation of cardiac baroreceptor reflexes activity by fu­rosemide that is independent of furos­emide renal effects. However, furose­mide had no effect on isolated rabbit heart. Also, we found that furosemide induced an activation of tonic