Infusion of atrial natriuretic hormone in DOCA/salt and spontaneously hypertensive rats

The effects of a 6-day infusion of atrial natriuretic hormone (ANH) on blood pressure and urinary sodium excretion were determined in conscious DOCA/salt and spontaneously hypertensive rats. The DOCA/salt rats were randomly divided into two groups after 4 weeks and either infused by osmotic minipump with 32.5 pmol/h of ANH in 0.1% gelatin vehicle or sham operated with emplacement of a blind cannula. Thirteen-week-old spontaneously hypertensive rats were studied in a similar fashion. The baseline systolic blood pressure prior to the infusion was 176 +/- 7 mmHg (x +/- SEM) in the ANH group and 169 +/- 5 mmHg in the sham group of DOCA/salt animals. The ANH infusion in the DOCA/salt animals dropped their blood pressure to 160 +/- 10 mmHg (p less than 0.01) compared to that in the sham controls which continued to rise to 200 +/- 7 mmHg. The blood pressure response to ANH infusion in the spontaneously hypertensive rats was slightly greater, with a blood pressure of 192 +/- 5 mmHg in the sham group and 132 +/- 3 mmHg in the ANH-infused animals. ANH infusion produces a qualitatively similar blood pressure response in the DOCA/salt rat as well as the other hypertensive models. This response is relatively less on a quantitative basis than that observed in the spontaneously hypertensive rats and is not related to changes in sodium balance or volume contraction.