TRANSVASCULAR ALBUMIN TRANSPORT AND PROTEIN REPLENISHMENT AFTER HEMORRHAGE IN THE CHRONICALLY CATHETERIZED PREGNANT RABBIT

Pregnancy is characterized by increases in both blood acid interstitia l volumes, but the mechanisms are unknown. To test the hypotheses that blood volume (BV) recovery after haemorrhage in pregnant (P) is faste r than in nonpregnant (NP) rabbits, and that this can be explained by a higher capillary filtration, a 20% BV haemorrhage was produced in a group of 7 P and 7 NP rabbits. We determined the BV recovery (measured by 99Tc), the total plasma protein mass and the haematocrit at 10, 20 , 30, 60 and 1440 min after haemorrhage. Arterial and venous pressures and heart rate were measured during a 30-min control period, during t he 10 min of haemorrhage, and for the following 70 min, In a separate group of P and NP rabbits, 125I-labelled albumin was infused and blood samples were obtained at 10, 20, and 30 min. Capillary filtration was expressed as the percentage of radioactive albumin that left the intr avascular space after 30 min. No differences were found in the rate of BV recovery, arterial and venous pressures, or heart rate response be tween P and NP animals (P>0.1). By 24 h total plasma protein mass (TPP M) was significantly increased above baseline in the P rabbits by an a verage + SEM of 13 + 3.7%, but not in NP rabbits (5 + 45%). At 30 min, the amount of labelled albumin in the intravascular space decreased b y 15.4 + 3.4% for P v. 8.2 + 1.2% for NP rabbits (P<0.05). There was a high correlation between TPPM recovery and BV recovery in the P (r = 0.96) and NP rabbits (r = 0.95), In conclusion, we did not find differ ences in the rate at which the BV recovered during pregnancy, despite the increased capillary permeability, During pregnancy the combination of the latter with an increase in the TPPM elevation above pre-haemor rhage levels suggests a faster rate of protein mobilization.