The effect of pitressin infusion on blood pressure of the rabbit, cat, and rat

1.1. Continuous intravenous infusion of pitressin is followed by an immediate rise in blood pressure which is scarcely sustained in the rabbit, moderately sustained in the cat, and continuously sustained in the rat.2.2. The failure of the rabbit to sustain a pressor response to a continuing infusion of pitressin appears related to the development of a marked refractory state, since even increasing the infusion to relatively massive amounts fails to prevent the return of the blood pressure toward normal levels.3.3. No marked changes in pulse pressure were observed in the rabbit or the cat while the sustained hypertension observed in the rat was uniformly accompanied by an increase in pulse pressure.4.4. Only transient irregularities in the electrocardiograph, a tendency to peaking of the T wave, were occasionally observed.