STIMULATION OF RENAL INTERSTITIAL BRADYKININ BY SODIUM DEPLETION

The ability to measure and detect change in renal bradykinin in situ w ould allow study of relations between local kinin production and renal function in hypertensive or diabetic disorders. A new renal interstit ial microdialysis technique allowed collections of renal subcapsular i nterstitial fluid 2 weeks after microdialysis probe placement in consc ious dogs (n = 5) on a normal sodium diet (50 mEq/day) and for 5 subse quent days on low sodium intake (10 mEq/day). Although interstitial br adykinin measured by radioimmunoassay (RIA) was undetectable (< 0.08 p g/min) during normal sodium intake, it was detectable (0.34 +/- 0.02 p g/min) after 1 day of low sodium. The kinin level at the end of the 5 subsequent days on low sodium was 1.94 +/- 0.09 pg/min (P < .01). The data show that renal interstitial kinin can be measured in situ. Furth er, a low sodium diet can rapidly increase interstitial kinin in the c onscious dog.