Effect of atrial peptide on collecting duct function.
1. The effects of synthetic rat atrial natriuretic peptides (ANP) on diffusional 22Na+, 36Cl- and tritiated water (THO) permeability of in vitro microperfused rat papillary collecting ducts and the effect in vivo of ANP on stop-flow sodium concentrations in the terminal segment of rabbit nephrons were studied. 2. The addition of 4 x 10(-8) or 4 x 10(-7) mol/l ANP to the medium or perfusion solution did not alter diffusional 22Na+ or 36Cl- permeability of microperfused rat papillary collecting ducts. 3. The basal diffusional THO permeability of papillary collecting ducts was not altered when 4 x 10(-7) mol/l ANP was present in the medium and did not inhibit the increment in diffusional THO permeability induced by vasopressin or reduce the permeability to water in a duct previously stimulated by vasopressin. 4. The administration of ANP (2 micrograms/kg bodyweight) to rabbits in water diuresis did not alter systemic blood pressure but induced a marked natriuresis and increases in urine flow and potassium excretion. This natriuresis was not associated with alterations in stop-flow sodium reabsorptive capacity or sodium permeability of the collecting tubules and ducts. 5. Previously reported in vivo clearance data suggest that ANP causes, at least in part, a natriuresis by altering sodium transport in the medullary collecting ducts. In this study, however, a direct effect could not be demonstrated and it is possible that the medulla needs to be functioning in its normal environment for such effects to be demonstrated.
Fitzgibbon
W
W
Department of Physiology, University of Melbourne, Parkville, Victoria, Australia.
Morgan
T
T
D000818:Animals; D009320:Atrial Natriuretic Factor / Q000494:pharmacology*; D002712:Chlorides / Q000378:metabolism*; D002713:Chlorine; D005260:Female; D005665:Furosemide / Q000494:pharmacology; D007679:Kidney Medulla / Q000187:drug effects / Q000502:physiology*; D008297:Male; D010539:Permeability; D011817:Rabbits; D011868:Radioisotopes; D051381:Rats; D011919:Rats, Inbred Strains; D012964:Sodium / Q000378:metabolism*; D012979:Sodium Radioisotopes; D014316:Tritium; D014867:Water / Q000378:metabolism
D002712:Chlorides; D011868:Radioisotopes; D012979:Sodium Radioisotopes; D014867:Water; D014316:Tritium; D002713:Chlorine; D005665:Furosemide; D009320:Atrial Natriuretic Factor; D012964:Sodium