LETHAL DOSE AND AVERAGE RATE OF UPTAKE OF G-STROPHANTHIN IN THE HEART-LUNG PREPARATION OF THE DOG UNDER VARYING CONDITIONS

¹ Department of Pharmacology, American University of Beirut, Beirut, Lebanon

Qualitative and quantitative changes in heart work of the H.L.P. do not significantly influence either the lethal dose, minimal lethal dose, or average rate of uptake of g-strophanthin in the H.L.P. of the dog. A decrease in blood volume decreases the lethal dose and increases the average rate of uptake when rates higher than the optimal rate of administration of g-strophanthin are employed. The minimal lethal dose is not changed by a change in blood-volume.

A reduction of the blood temperature increases the lethal dose and decreases the average rate of uptake and optimal rate of administration. The minimal lethal dose of g-strophanthin is not influenced by a change in the blood temperature from 35 to 39°C.

Sublethal doses of barium chloride, as well as the increase in heart rate and other metabolic changes produced by epinephrine do not change the L.D., M.L.D., or average rate of uptake of g-strophanthin in the heart-lung preparation of the dog.

Caffeine and sodium benzoate increases the average rate of uptake but does not influence the M.L.D. of g-strophanthin.

No differences in sensitivity to digitoxin can be detected between intact anesthetized (sodium pentobarbital) pups and adult dogs. The minimal lethal dose of g-strophanthin and digitoxin determined in the H.L.P. of young dogs does not appear to be significantly different from the M.L.D. determined on the H.L.P. of adult dogs.