RADIOIMMUNOASSAY OF ARGININE VASOPRESSIN IN THE PLASMA AND URINE

  • 1 January 1979
    • journal article
    • research article
    • Vol. 28  (5) , 399-409
Abstract
The radioimmunoassay [RIA] of arginine vasopressin [AVP] was employed with standard AVP and antiserum to AVP [both Calbiochem]. The sensitivity of the system was increased from the declared 4 pg to 1 pg/tube by preparing AVP-125I of high specific activity [about 1500 mCi/mg] and by modifying the reaction conditions. The sensitivity of the method was adequate for measuring AVP in urine and in concentrated plasma extracts, even under physiological conditions. Reliability of the results depended upon maintenance of approximately the same osmolarity in all the RIA samples. The mean plasma AVP level, uncorrected for AVP extraction losses, was 1.52 .+-. 0.20 pg/ml for an ad lib fluid intake; in fluid deprivation it rose in proportion to the osmolarity of the plasma to 5.83 .+-. 0.42 pg/ml at 12 h and to 19.09 .+-. 4.51 pg/ml at 36 h. Extraction recovery of added AVP was about 63%. The urinary AVP concentration varied according to the patients'' state of hydratation from undetectable values of UOsm < 200 mOsm[osmoles]/l to a mean 16.5 .+-. 7.9 pg/ml in the presence of an ad lib fluid intake and to 29.1 .+-. 7.5 pg/ml after 12 h and 117.2 .+-. 13.7 pg/ml after 36 h deprivation of fluids.