Renal nerve activity and renal function during environmental stress in DOCA-NaCl rats.

The effects of a stressful environmental stimulus (air stress) on mean arterial pressure, heart rate, renal sympathetic nerve activity, and renal function were studied in conscious deoxycorticosterone acetate-sodium chloride (DOCA-NaCl) hypertensive rats, sham DOCA-NaCl normotensive rats, and DOCA-NaCl rats with renal denervation. In conscious DOCA-NaCl hypertensive rats, air stress decreased urine flow rate [36% from 17.9 +/- 3.0 microliter X min-1 X 100 g body wt-1 (BW)], urinary sodium excretion (39% from 3.1 +/- 0.5 microeq X min-1 X 100 g BW-1), fractional water excretion (24% from 4.72 +/- 1.00%), and fractional sodium excretion (28% from 5.72 +/- 1.08%) and increased renal sympathetic nerve activity (94% from 8.3 +/- 0.6 integrator resets/min), but no changes occurred in glomerular filtration rate (-15% from 0.40 +/- 0.06 ml X min-1 X 100 g BW-1) or effective renal plasma flow (-7% from 2.50 +/- 0.53 ml X min-1 X 100 g BW-1). Air stress had no effect on these measures in conscious sham DOCA-NaCl normotensive rats or DOCA-NaCl rats with renal denervation. Mean arterial pressure and heart rate were unaffected by air stress in these three groups. Renal denervation lowered base-line mean arterial pressure in DOCA-NaCl rats. Thus DOCA-NaCl hypertensive rats respond to environmental stress with increased renal sympathetic nerve activity and, consequently, antidiuresis and antinatriuresis.