Renal function has been studied by the clearance (cl.) method during hypotonic
polyuria--four 15-min cl. periods--and successive antidiuresis--two 60-min cl. periods (A1, A2)--induced by lysine-8-vasopressin (LVP), 5 mU in bolus followed by infusion at a rate of 0.04 mU/min. The endogenous
creatinine cl. (Cc) and the osmotic cls. (Cosm, CH2O) were determined by the usual methods as well as the absolute and fractional urinary excretions of water,
sodium, chloride and
potassium. The urinary concentrations of
PGE2,
6-keto-PGF1 alpha and TxB2 were determined by the RIA method. This study protocol has been applied to 20 healthy women submitted to paired functional explorations in both the absence and presence of
indomethacin (100 mg i.m.); the
drug effects have been evaluated in both normal
potassium balance (N2, n = 6) and in two groups of
potassium depletion (KD) with
potassium cumulative deficit of 160 +/- 43 (D2, n = 8) and 198 +/- 22 meq (D3, n = 6), respectively. As regards the early % effects of LVP, i.e. (A1-P)% of P (mean
polyuria), the inhibition of
prostanoid synthesis with
indomethacin produced significant changes: 1) an enhanced reduction in renal
chloride excretion in all experimental groups; 2) a reduction in renal
sodium and
chloride fractional excretions in both KD groups; 3) an enhanced
antidiuretic effect in D3 only, i.e. in the experimental condition with inhibition of
prostanoid renal synthesis present during the control study.