抄録
Ephedrine was stttdied cxjcerimentally for inafltuence tupon the running per-formance of race horses. Three Uhorotughbred horses were i?tjected subcutaneously witlaa single dose of 150, 300, ancl 500 Illg of epheclrine hydroclnlc>ricle, respectively, and sub-jected to an exercise which started al>out l hour a.fter the iunjection. The experimentalprocedure used was the same as mentioned in the previous rcrport.Ephedrine showed a performance-increasing effect with connsiderable individual differ-ences. Neither running-away frovn the track nor discontintuance of running due to a toomuch increased speed, botlt of which had been obs<:rved in tlte case of caffeine, occurredeven after administration with 500 mg. It increased the heart rate during the exercise inproportion to tlte work rate, and raised marl<edly the ratio of the height of the post-exercise T wave of tlte electrocarcliogram (ECG) to tlaat of tlae pre-exercise T wave forthe first 2 to 3 minutes in the stage of recovery.On the other hand, epheclrine ittduced infrequent extrasystc>les during the exercise andvery frequent second-degree A-V blocks in the very early stage of recovery. Consecutivesecond-degree A-V blocks and S-A blocks were also observed. Ephedrine brought about anincrease in the respiratory rate during the period of standi?tg before the exercise. Itsinfluence upon the respiratory rat.e, however, was su)cpressed dtaring the exercise, and onlydeepened respiration was observed. Immediately after the exercise, its influence recurred.It caused restlessness in some horses after tlae exercise. The re;;tlessness was not so seriousas to make the Iaorses unmanageable. These results indicate tltat ephedrine is inferior tocaffeine to a considerable extent in the performance-increasinag effect and that, on thecontrary, the drug is more hazardous to tlte health of horses than caffeine.
