Renal Interstitial Fluid Angiotensin

Using a microdialysis technique, we monitored changes in right and left renal interstitial fluid angiotensins in anesthetized and conscious dogs (both n = 5) in response to right renal interstitial epinephrine (0.2 mg/kg per minute) administration. Renal interstitial and plasma angiotensin levels also were monitored in conscious dogs (n = 4) in response to dietary sodium deprivation (10 mmol/d) for 5 consecutive days. Changes in renal interstitial and plasma angiotensins in response to interstitial administration of a specific renin inhibitor, ACRIP (0.5 micrograms/kg per minute for 20 minutes), were monitored on day 5 of sodium depletion. At basal levels, there were no significant differences between the right and left renal interstitial immunoreactive angiotensin levels in anesthetized dogs. Renal interstitial epinephrine administration caused a significant increase in renal interstitial immunoreactive angiotensin concentrations in both anesthetized and conscious dogs (P < .01). However, anesthetized dogs had significantly higher renal interstitial immunoreactive angiotensin levels basally and in response to epinephrine than conscious dogs (P < .05). Renal interstitial immunoreactive angiotensin concentrations increased significantly and progressively during exposure to a low sodium diet from 3.9 +/- 1 nmol on day 1 to 740 +/- 332 nmol on day 5 (P < .01). Renal interstitial immunoreactive angiotensin decreased significantly to 124 +/- 37 nmol (P < .01) in response to intrarenal renin inhibition at the end of day 5 of sodium depletion. Plasma immunoreactive angiotensin increased significantly (P < .01) in response to sodium depletion, and no change occurred during intrarenal renin inhibition.(ABSTRACT TRUNCATED AT 250 WORDS)