Premium
MODES OF INACTIVATION OF NEUROHYPOPHYSIAL HORMONES: SIGNIFICANCE OF PLASMA DISAPPEARANCE RATE FOR THEIR PHYSIOLOGICAL RESPONSES
Author(s) -
PLIŜKA VLADIMIR,
RUDINGER JOSEF
Publication year - 1976
Publication title -
clinical endocrinology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.055
H-Index - 147
eISSN - 1365-2265
pISSN - 0300-0664
DOI - 10.1111/j.1365-2265.1976.tb03817.x
Subject(s) - medicine , endocrinology , hormone , chemistry , biology
SUMMARY Analogues of oxytocin and deaminooxytocin with 4‐glutamine replaced by 4‐glutamic acid methyl ester readily lose their uterotonic activity when incubated with rat serum, presumably by hydrolysis to the much less active 4‐glutamic acid derivatives. On the other hand, inactivation of the deaminooxytocin analogue in the rat uterus, as demonstrated by the ‘oil‐bath’technique, is only slightly more rapid than that of deaminooxytocin and distinctly slower than that of oxytocin. Its in situ/in vitro ratio of uterotonic activity is less than 0.1 whereas that for deaminooxytocin is about 3 and also the persistence of the uterotonic effect in situ is slightly less than that of deaminooxytocin. The results with these ‘rapidly inactivated’analogues can be used as proof of some predictions of the three‐compartment model for tissue distribution of neurohypophysial hormones and its influence upon the time course of a biological response published earlier. The potential use of analogues of neurohypophysial hormones as probes for inactivation mechanisms and the results thus far obtained are discussed.