ENDOGENOUS PLASMA ATRIAL-NATRIURETIC-PEPTIDE AND THE CONTROL OF SALT-GLAND FUNCTION IN THE PEKIN DUCK

Polyclonal antibodies raised in a rabbit against avian atrial natriure tic peptide (ANP) were used to investigate the role of endogenous plas ma ANP in the control of salt gland function of conscious, saltwater-a dapted Pekin ducks. Salt gland secretion was initiated and maintained either by a hypervolemic (290 mosmol/kg NaCl iv at 2 ml/min) or hypero smotic (1,000 mosmol/kg NaCl iv at 0.4 ml/min) stimulus. Both experime ntal conditions caused significant Elevations in endogenous plasma ANP concentrations. At steady states of secretion driven by hypervolemia, the administration of ANP antiserum (anti-ANP), which reduced plasma ANP concentrations by 90%, caused an immediate 30% reduction in fluid secretion rate and sodium excretion that lasted for 20-30 min. The act ivity of salt glands driven by hyperosmolality was not changed by anti -ANP. The results show that the high circulating concentrations of end ogenous ANP associated with conditions of sustained volume expansion p romote salt gland secretion.