We investigated the relationship between mean circulatory filling pressure (MCFP) and blood volume in nonpregnant (NP), estrogen-treated (E), and pregnant (P) guinea pigs. Reversible circulatory arrest was produced by rapid ventricular pacing or acetylcholine in unanesthetized animals remote from surgery. MCFP (mmHg) was higher for E (7.1 ± 0.3) than for NP (5.8 ± 0.5) or P (5.3 ± 0.4). The gradient for venous return, the difference between MCFP and right atrial pressure (mmHg), did not differ in NP-(6.0 ± 0.5), P- (5.8 ± 0.5), or E- (5.8 ± 0.4) treated animals. Capacitance, the blood volume (ml/kg) at an MCFP of 6 mmHg, was increased in P (84 ± 6) and E (89 ± 7), compared with NP (64 ± 5) animals. Compliance, the ratio of the change in volume to change in pressure in the range of 6-12 mmHg (ml · kg-1 · mmHg-1), was greater in P (4.4 ± 0.3) than NP (3.5 ± 0.3) animals. Hexamethonium blockade did not affect MCFP, capacitance, or compliance. We conclude that the effect of blood volume expansion on the circulation in pregnancy cannot be predicted from knowledge of MCFP-blood volume relationships in the nonpregnant animal, because capacitance and compliance are altered. Estrogen administration to nonpregnant animals reproduces some of these effects.
|Original language||English (US)|
|Journal||American Journal of Physiology - Regulatory Integrative and Comparative Physiology|
|State||Published - Jan 1 1989|
- mean circulatory filling pressure
ASJC Scopus subject areas
- Physiology (medical)