Kj. Gibson et Er. Lumbers, OVINE FETAL CARDIOVASCULAR, RENAL, AND FLUID BALANCE RESPONSES TO 3 DAYS OF HIGH ARGININE-VASOPRESSIN LEVELS, American journal of physiology. Regulatory, integrative and comparative physiology, 41(4), 1997, pp. 1069-1076
To determine the effects of sustained high levels of arginine vasopres
sin (AVP) on the fetus and whether these effects were the same as thos
e found during acute infusion of AVP, chronically catheterized fetal s
heep aged 121-136 days were infused for 3 days with either AVP (45 mU.
kg(-1).h(-1)) or saline. The bradycardia, acidemia, and failure of glo
merulotubular balance that occurred with acute AVP infusion were rever
sed by day 3 of AVP (P < 0.005) and the acute rise in arterial pressur
e was attenuated (P < 0.005). By contrast, the rise in the glomerular
filtration rate was sustained (P < 0.005) and urinary osmolality incre
ased further to 426 +/- 30 mosmol/kg (P < 0.01). Although placental bl
ood flow did not change acutely with AVP, it had fallen by day 3 (P <
0.01). In addition, with AVP but not saline extracellular volume fell
from 588 +/- 28 to 493 +/- 29 ml/kg (P < 0.002) and the plasma/interst
itial volume ratio rose from 0.18 +/- 0.01 to 0.21 +/- 0.01 (P = 0.001
). These findings suggest that although release of ANP may be benefici
al in acute stress in utero, sustained high levels may be detrimental
to fetal health and sodium balance.