Blood pressure responses to ACTH and adrenaline infusions in dogs

The hypothesis that interactions between adrenaline and adrenal cortical hormones may increase arterial blood pressure has been examined in trained dogs with chronically indwelling aortic and venous catheters. The dogs received continuous infusions for 4 days of ACTH (400 micrograms/day), or adrenaline (8 mg/day) or both ACTH and adrenaline, or saline vehicle. Compared to pre-infusion control values, ACTH raised mean arterial pressure by 14.9 +/- 2.2 mmHg by the 4th day of infusion, adrenaline infused alone had no effect (-0.2 +/- 3.9 mmHg), and ACTH and adrenaline infused together raised pressure 13.1 +/- 3.2 mmHg (not significantly different to ACTH alone). ACTH increased water consumption, Na+ and K+ excretion and creatinine clearance by the 4th day of infusion and these effects were not significantly altered when adrenaline was also infused. Thus adrenaline did not potentiate the hypertension produced by ACTH administration.