Journal of Applied Physiology, Vol 72, Issue 3 993-997, Copyright © 1992 by American Physiological Society
Atrial natriuretic factor and renal sodium excretion during ventilation with PEEP in hypervolemic dogs
G. Christensen, J. F. Bugge, J. Ostensen and F. Kiil
Institute for Experimental Medical Research, University of Oslo, Ullevaal Hospital, Norway.
Controlled mandatory ventilation with positive end-expiratory pressure
(PEEP) reduces renal sodium excretion. To examine whether atrial
natriuretic factor (ANF) is involved in the renal response to alterations
in end-expiratory pressure in hypervolemic dogs, experiments were performed
on anesthetized dogs with increased blood volume. Changing from PEEP to
zero end-expiratory pressure (ZEEP) increased sodium excretion by 145 +/-
61 from 310 +/- 61 mumol/min and increased plasma immunoreactive (ir) ANF
by 104 +/- 27 from 136 +/- 21 pg/ml. Changing from ZEEP to PEEP reduced
sodium excretion by 136 +/- 36 mumol/min and reduced plasma irANF by 98 +/-
22 pg/ml. To examine a possible causal relationship, ANF (6 ng.min-1.kg
body wt-1) was infused intravenously during PEEP to raise plasma irANF to
the same level as during ZEEP. Sodium excretion increased by 80 +/- 36 from
290 +/- 78 mumol/min as plasma irANF increased by 96 +/- 28 from 148 +/- 28
pg/ml. We conclude that alterations in end-expiratory pressure lead to
great changes in plasma irANF and sodium excretion in dogs with increased
blood volume. Comparison of the effects of altering end-expiratory pressure
and infusing ANF indicates that a substantial part of the changes in sodium
excretion during variations in end-expiratory pressure can be attributed to
changes in plasma irANF.
