Diurnal variation of plasma arginine-vasopressin in pregnant and non-pregnant goats (Capra hircus)

Abstract

The aim of this study was to estimate and analyse daily profiles of plasma arginine-vasopressin concentration (AVP), sodium, potassium, chloride concentrations and the plasma osmolality (PO) in pregnant (n = 9) and non-pregnant (n = 17) goats. The influence of late pregnancy on AVP diurnal changes and correlation between PO and electrolyte concentrations were determined. Plasma AVP in both groups of goats changed during 24 h, with the highest values in the dark phase and lowest values during the light phase. AVP in pregnant goats ranged from 0.66 fmol·ml-1 to 1.14 fmol·ml-1 and was higher than that in non-pregnant goats (0.48-0.83 fmol·ml-1), especially during the dark phase. Relatively stabilised concentration of osmotic active electrolytes in plasma in both groups of goats suggests the efficiency of the processes protecting the water-electrolyte homeostasis, which is especially significant in pregnancy.