DIE INAKTIVIERUNG VON INFUNDIERTEM VASOPRESSIN BEI DIABETES INSIPIDUS-PROBANDEN

Abstract

ABSTRACT 30 experiments were performed in 6 human subjects with diabetes insipidus of the central type. The response of the target organ has been investigated after abrupt cessation of a several hours lasting vasopressin infusion of different dosage. Thereby only the decrease of the urinary osmolality followed about a simple exponential decline after a different time of latency. The mean values of vasopressin doses correlated with the urinary osmolalities at the end of the infusions, the latent periods and the »slopes of the osmolar decrease«. After an input rate of 6.7 ± 3.2 μU vasopressin/kg/min, the »half life of response« was 8.25 ± 2 min, and the latent period after the withdrawal of infusion until the beginning to decline amounted to 28.45 ± 8.5 min. The corresponding data of an infusion rate of 1.7 μU/kg/min were a »half life« period of 21.7 ± 6.15 min and a time of latency of 5.1 ± 3.2 min. The total time of decrease in urinary concentration, averaging 29 min, remained completely constant in all the tests, and it was not influenced by the hormonal dosis. Only in 16 experiments, however, the time of observation had been extended until the osmolality had diminished below 100 mOsm/kg. Here the duration of the decline lasted 32.1 min on average. Therefore it was supposed a real »time of detectable inactivation« of 32 to 35 min. From the obtained results a theory is discussed, concerning the quantitative relation between vasopressin and the receptor of the target organ, and the mode of inactivation occurring there.