Hp. Henneberry et al., ARGININE VASOPRESSIN RESPONSE TO HYPERTONICITY IN HYPERTENSION STUDIED BY ARGININE VASOPRESSIN ASSAY IN UNEXTRACTED PLASMA, Journal of hypertension, 10(3), 1992, pp. 221-228
Objective: To investigate whether plasma osmolality (P(osm))-plasma ar
ginine vasopressin (P(AVP)) response relationships with particular cha
racteristics of sensitivity, gain or response pattern (linear/non-line
ar) occur more frequently in hypertensive than normotensive subjects.
Design: Analysis of P(osm)-P(AVP) curves observed in individual normot
ensive and hypertensive subjects rather than whole groups was consider
ed appropriate for the described objective. Methods. A sensitive and p
recise radioimmunoassay of P(AVP) in unextracted plasma was developed.
P(osm) was raised in 11 normotensive and 19 hypertensive subjects by
infusion of NaCl solution (0.86 mol/l, i.v.), and P(AVP) assayed at in
tervals. Best-fitting linear and non-linear equations for the P(osm)-P
(AVP) relationship were established by computer. Results: The mean ris
e in osmolality, blood pressure and blood volume was similar in the tw
o groups. Hypertensive subjects showed a tendency towards higher rates
of response (pmol AVP/l per mosm per kg) at P(osm) > 290 mosm/kg, lea
ding to a non-linear response pattern compared with the normotensive s
ubjects. Conclusions: The enhanced P(AVP) responses found in the hyper
tensive subjects at P(osm) > 290 mosm/kg may reinforce vascular and ce
ntral nervous pathogenetic mechanisms.