Abstract
The effects of α-human atrial natriuretic peptide (α-hANP) on cortisol (F) and aldosterone (Aid) productions were investigated in 6 patients with essential hypertension (4 males, 2 females) during an administration of low dose adrenocorticotropic hormone (ACTH). They received an intravenous infusion of synthetic ACTH (0.7 ng/kg/min) for 60 min on one day and an intravenous infusion of ACTH and synthetic α-hANP (0.1 fig/ kg/min) for 30 min on another day. Synthetic α-hANP infusion significantly reduced blood pressure (p<0.01) and increased heart rate (p<0.01) compared to their basal levels. These changes disappeared within 30 min after the cessation of α-hANP infusion, Although urinary sodium and potassium excretions, and glomeruiar filtration rate were not changed significantly by the infusion of ACTH with α-hANP, urine volume was signi-ficantly (p<0.05) increased after α-hANP infusion. Increment of free water reabsorption significantly (p<0.05) decreased after administration of ACTH with a-hANP compared with that after ACTH administration alone. There was no significant effect on F and Aid productions during the administration of low dose ACTH. Although synthetic α-hANP infusion reduced plasma levels of ADH, there was no significant difference as compared with plasma ADH levels after ACTH administration alone, Although plasma norepinephrine levels were elevated after α-hANP infusion, plasma epinephrine and dopamine levels were not significant changed. Thus it seems likely that the dose of α-hANP used in our study has no effect on F and Aid production during an administration of low dose ACTH in vivo and that the inhibition of free water reabsorption contributes to the diuretic action of α-hANP.
