Temporal relations of the endocrine response to hypotension with sodium nitroprusside

Sodium nitroprusside was infused intravenously for 10 minutes in normal men, reclining at 45 degrees, in a dose sufficient to decrease the arterial pressure by 10 mmHg. The effect on a variety of plasma hormones was measured during the infusion and for 20 minutes afterwards. The heart rate increased to a maximum of 149%. Norepinephrine rose to a maximum of 196% in 5 minutes. Epinephrine reached a peak of 207% after 10 minutes. Plasma renin activity reached a peak of 449% at 10 minutes. Aldosterone did not change during the infusion, but increased to a maximum of 145% 10 minutes later. Vasopressin increased sharply at the end of the infusion to 893% and then rapidly decreased. Corticotropin, prolactin and growth hormone started to increase toward the end of the infusion, but reached their maxima during recovery. Corticotropin (225%) and prolactin (288%) peaked 10 minutes after the infusion, while growth hormone (414%) appeared still to be rising 20 minutes after the end of the infusion. Cortisol also rose progressively during recovery to a level of 138%. No significant changes were seen in the concentrations of insulin, glucagon, atrial natriuretic peptide, bombesin or neurotensin.