title: Interference in the cytochemical assay of plasma vasopressin by a circulating factor induced by salt-loading in man.
abstract: Infusion of hypertonic saline into six normal volunteers caused an increase in plasma osmolality from 286.8 +/- 1.7 (mean +/- S.E.M.) to 307.6 +/- 2.6 mosmol/kg (P less than 0.001), a 7.1% increase in estimated blood volume, a rise in plasma immunoreactive arginine vasopressin (AVP) concentrations from 1.3 +/- 0.2 to 12.7 +/- 3.6 pmol/l (P less than 0.001) but no change in plasma AVP concentrations (2.1 +/- 0.9 and 1.9 +/- 1.3 pmol/l) as measured by a cytochemical technique based on the ability of AVP to stimulate rat renal medullary Na+/K+-ATPase activity. Addition of synthetic AVP to plasma obtained before, during and after hypertonic saline infusion also failed to stimulate Na+/K+-ATPase activity. The results suggest that infusion of hypertonic saline interfered with the cytochemical assay for AVP by inhibiting AVP-stimulated medullary Na+/K+-ATPase activity. We conclude that the use of this cytochemical method to detect plasma AVP has severe limitations under these experimental conditions.
mesh_terms: D000328:Adult; D001127:Arginine Vasopressin / Q000097:blood* / Q000494:pharmacology; D005260:Female; D006400:Hematocrit; D006651:Histocytochemistry; D006801:Humans; D066298:In Vitro Techniques; D007679:Kidney Medulla / Q000187:drug effects; D008297:Male; D009994:Osmolar Concentration; D012462:Saline Solution, Hypertonic / Q000494:pharmacology*; D012965:Sodium Chloride / Q000494:pharmacology*; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism
chemical_list: D012462:Saline Solution, Hypertonic; D001127:Arginine Vasopressin; D012965:Sodium Chloride; D000254:Sodium-Potassium-Exchanging ATPase