EFFECT OF LIGNOCAINE ON ARGININE-VASOPRESSIN PLASMA-LEVELS - BASE-LINE OR INDUCED BY FRUSEMIDE

1 To assess whether or not lignocaine influences baseline and frusemide-induced (5 mg kg-1) plasma concentrations of arginine-vasopressin (AVP), 2 groups of rabbits received an infusion of lignocaine (130-mu-g min-1 kg-1) for 6 h. Lignocaine-induced changes in AVP plasma concentrations were substantiated by measurement of diuresis and natriuresis and hepatic plasma flow, by means of an infusion of indocyanine green (ICG) (249-mu-g min-1 kg-1). 2 Baseline plasma AVP levels were 4.9 +/- 0.9 pg ml-1 (+/- s.e.), and following lignocaine, these values were reduced to 0.7 +/- 0.1 pg ml-1 (P<0.01). Frusemide increased AVP levels to 134.1 +/- 73.6 pg ml-1 (P<0.05) and lignocaine totally prevented this increase, e.g. mean AVP levels of 2.7 pg ml-1. 3 Lignocaine enhanced baseline diuresis secondary to an increase in free water clearance; none of the experimental conditions affected the diuresis and natriuresis induced by frusemide. 4 Frusemide reduced the hepatic plasma flow and this decrease was not reversed by the infusion of lignocaine. 5 It is concluded that in healthy rabbits lignocaine reduces baseline secretion of AVP and its antidiuretic effect; in addition, lignocaine prevents the rise in AVP induced by frusemide.