title: Renal effects of overhydration during vasopressin infusion in conscious dogs.
abstract: The antidiuretic and possibly natriuretic effects of small doses of vasopressin (AVP) were investigated in conscious dogs. Plasma composition and renal excretion of water, Na+, and K+ were measured after overhydration by 20 ml/kg performed during infusion of AVP at rates of 50, 100, 150, 200, or 400 pg X min-1 X kg body wt-1 or of 1-desamino-8-D-arginine vasopressin (DDAVP) 50 pg X min-1 X kg body wt-1. Hydration lowered plasma osmolality and sodium concentration by 4.2 +/- 0.3 and 3.8 +/- 0.2%, respectively; plasma protein showed a larger decrease, 8.5 +/- 0.4% (P less than 0.01). Urine osmolality during hydration was 52 +/- 3 mosmol/kg H2O. AVP infusion at 100 pg X min-1 X kg-1 elevated plasma vasopressin by 1.7 +/- 0.3 pg/ml and urine osmolality by 1,049 +/- 152 mosmol/kg H2O and elicited marked natriuresis and kaliuresis but no change in osmolar clearance. During DDAVP infusion urine osmolality was 1,365 +/- 134 mosmol/kg H2O, but electrolyte excretion was indistinguishable from control. It is concluded that 1) AVP is associated with marked natriuresis and kaliuresis even in doses required to prevent water diuresis, 2) DDAVP--although strongly antidiuretic--does not affect electrolyte excretion, and 3) the water load causes disproportionate dilution of plasma protein and osmolality, probably due to protein redistribution.
mesh_terms: D000818:Animals; D001798:Blood Proteins / Q000378:metabolism; D004231:Diuresis / Q000187:drug effects*; D004285:Dogs; D005260:Female; D007668:Kidney / Q000187:drug effects* / Q000502:physiology; D008297:Male; D009318:Natriuresis / Q000187:drug effects; D009994:Osmolar Concentration; D011188:Potassium / Q000378:metabolism; D012964:Sodium / Q000378:metabolism; D013997:Time Factors; D014882:Water-Electrolyte Balance / Q000187:drug effects*
chemical_list: D001798:Blood Proteins; D012964:Sodium; D011188:Potassium