The hemodynamic profile of DOCA‐salt hypertension in 2‐kidney (2K) and 1‐kidney (1K) rats.

To establish the hemodynamic profile mechanisms of DOCA‐salt hypertension, rats were chronically instrumented for continuous high frequency measurement of mean arterial pressure (MAP) by telemetry and cardiac output (CO) using a Transonics flow probe on the ascending aorta. Experimental groups included animals with (1K;n=8) and without (2K;n=5) unilateral nephrectomy. Rats consumed water for one week and were then switched to 0.9% saline for one week prior to subcutaneous implantation of 50mg DOCA. During the saline control period, basal values for MAP, CO, heart rate (HR) and total peripheral resistance (TPR=MAP/CO) were similar in 2K and 1K rats. 3 weeks after of DOCA implantation, the increase in MAP in 1K rats (32.5 ± 7.4%) was nearly twice that of 2K rats (16.9 ± 5.3%). However, the temporal pattern of the hemodynamic profile was similar in both groups and was characterized by an initial increase in CO which returned to control levels, in contrast to a delayed increase in TPR which was sustained. 27 days after DOCA implantation, rats were switched from 0.9% saline back to water for 15 days to illicit an “off‐response”. Although MAP did decrease, it did not return to control levels in either group, and 1K rats exhibited a more modest recovery than 2K rats falling to ~25% and ~3% above control respectively. We conclude that the magnitude of the hypertensive response to DOCA‐salt is greater in 1K versus 2K rats but the temporal pattern of the hemodynamic profile is the same. Supported by NIH Grant HL 064178.