THE ANTIACCELERATOR EFFECT OF SPARTEINE ON THE HEART-LUNG PREPARATION OF THE DOG

¹ Department of Pharmacology, Harvard Medical School, Boston

In the heart-lung preparation of the dog with a blood volume of about one liter and working under standard conditions, the alkaloid sparteine, in a dosage range of 5 to 100 mgm. exhibits a negative chronotropic action which is not influenced by 1:100,000 (w/v) atropine sulfate.

In the dose of 20 mgm. and above sparteine causes a negative inotropic action which can be prevented by pretreatment with 25 to 50 microgm. of ouabain without interference with the negative chronotropic action.

Sparteine antagonizes the cardioaccelerator action of epinephrine or of ephedrine in a manner similar to that of veratramine. Like veratramine, sparteine is capable of separating the positive inotropic action of epinephrine from its positive chronotropic action.

Using 3 mgm. ephedrine to cause maximal cardioacceleration and determining the molar dose required to produce 50 per cent inhibition of acceleration, the antiaccelerator potency of sparteine was found to be 1/260 that of veratramine.