EFFECTS OF SODIUM CROMOGLYCATE ON LUNG IRRITANT RECEPTORS AND LEFT-VENTRICULAR CARDIAC RECEPTORS IN THE ANESTHETIZED DOG

The time from the injection of sodium cromoglycate 10 to 50 μg/kg into a saphenous vein, the cervical carotid arteries, the left ventricle and the aortic arch, to the onset of reflex hypotension has been measured in anaesthetized dogs. The shortest latency was 16.9 s on injection of sodium cromoglycate into the left ventricle. Instillation of 2% lignocaine into the pericardium of an anaesthetized dog blocked the reflex hypotensive response to sodium cromoglycate (10 to 50 μg/kg i.v.), and also prevented sodium cromoglycate (100 μg/kg) from reversing reflex bronchoconstriction induced by inhalation of an aerosol of histamine. The effect of sodium cromoglycate (100 μg/kg i.v.) on resting discharge and histamine‐induced discharge (20 μ/kg i.v.) of five lung irritant receptors in five anaesthetized dogs has been studied. Sodium cromoglycate (100 μg/kg i.v.) did not affect the resting discharge of these receptors or their ability to respond to histamine. Sodium cromoglycate (100 μg/kg i.v.) increased the rate of discharge of three receptors found in the endocardium of the left ventricle of the canine heart. A solution of sodium cromoglycate (0.1%) was applied topically to one receptor and its rate of discharge was increased. It is suggested that in the dog, sodium cromoglycate produces reflex hypotension and reverses histamine‐induced reflex bronchoconstriction by activating receptors in the left ventricle of the heart. 1979 British Pharmacological Society