Urinary guanosine 3':5'-cyclic monophosphate but not tissue kallikrein follows the plasma atrial natriuretic factor response to acute volume expansion with saline.

1. The relationship between plasma immunoreactive atrial natriuretic factor (Ir-ANF) and the urinary excretion of sodium, guanosine 3':5'-cyclic monophosphate (cyclic GMP) and of tissue kallikrein was examined in seven healthy female volunteers. 2. Each volunteer attended on two occasions, a control and a saline infusion day. On the infusion day saline (2 litres, 0.9% NaCl) was administered over 60 min. Measurements of plasma Ir-ANF and urinary excretion of sodium, cyclic GMP and of tissue kallikrein were made at 30 min intervals during the infusion and for 3 h after the infusion. 3. Mean (+/- SEM) urinary sodium excretion increased from a basal value (time 0) of 102 +/- 15 mumo/min to 222 +/- 47 mumol/min 60-90 min from the start of the infusion and thereafter remained significantly elevated (P less than 0.01) above sodium excretion on the control day. 4. In response to saline infusion there was a transient rise in mean (+/- SEM) plasma Ir-ANF from 6.7 +/- 0.8 pmol/l to a peak of 22.5 +/- 3.7 pmol/l at 75 min, falling to 12.7 +/- 1.9 pmol/l at 135 min. The peak plasma Ir-ANF level on the infusion day was significantly elevated (P less than 0.05) above the time-matched measurement on the control day. 5. Similarly, there was a transient rise in mean (+/- SEM) urinary cyclic GMP excretion on the infusion day from 30.9 +/- 4.4 fmol/min to 64.6 +/- 11.4 fmol/min during the 60-90 min collection period, returning to 43.7 +/- 14.5 fmol/min at 210-240 min.(ABSTRACT TRUNCATED AT 250 WORDS)