Lm. Slimmer et Ml. Blair, FEMALE REPRODUCTIVE-CYCLE INFLUENCES PLASMA-VOLUME AND PROTEIN RESTITUTION AFTER HEMORRHAGE IN THE CONSCIOUS RAT, American journal of physiology. Regulatory, integrative and comparative physiology, 40(3), 1996, pp. 626-633
The present study was designed to test the hypothesis that gender and
female reproductive cycle phase influence the restitution of blood vol
ume following blood loss. The experiments were performed in conscious
9- to 11-wk-old Sprague-Dawley rats subjected to a slow hemorrhage of
19 ml/kg over 40 min. The effect of hemorrhage was compared in male ra
ts and in female rats in either proestrus (Pro) or metestrus (Met). In
comparison with either metestrus females or males, females hemorrhage
d on the morning of proestrus showed a significantly larger overall de
crease in percent hematocrit (Pro, -17+/-1; Met, -10+/-1; male, -13+/-
1; mean+/-SE), increase in plasma volume (Pro, to 151+/-15% of initial
volume; Met, 104+/-8%; male, 120+/-4%), and increase in total plasma
protein content (Pro, to 164+/-14% of initial content; Met, 101+/-5%;
male, 132+/-5%) over the 21-h posthemorrhage recovery period. Proestru
s females also showed a larger increase in plasma osmolality during th
e first 2.5-h posthemorrhage than either metestrus females or males (P
<0.05). In addition, basal hematocrit and total blood volume (Cr-51-t
agged erythrocyte method) were higher in females studied on the mornin
g of proestrus than in metestrus females. These results indicate that
the female reproductive cycle is an important variable in basal blood
volume regulation and in plasma protein and plasma volume restitution
following blood loss.