I004: Spontaneous sustained pregnancy-associated hypertension in SHHF/Mcc-facp rats: A possible model for impaired blood pressure regulation in pregnant women

• Published in: American journal of hypertension Vol. 13; no. S2; p. 277A
• Main Authors: Sharkey, L.C., McCune, S.A., Fray, J.C.S.
• Format: Journal Article
• Language: English
• Published: Oxford Oxford University Press 01.04.2000
• Subjects: hypertension-associated pregnancy; Preeclampsia; small birth weight
• ISSN: 0895-7061; 1941-7225
• DOI: 10.1016/S0895-7061(00)01024-4

Hypertension is a major contributor to maternal and fetal morbidity and mortality, with the potential to result in maternal death, intrauterine growth retardation, and the need for iatrogenic preterm delivery of infants. Progress in understanding the pathogenesis of hypertensive disorders of pregnancy has been slowed by the scarcity of animal models that develop the disorders spontaneously and in so doing model the situation in humans. Twenty nulliparous 5-month-old female SHHF/Mcc-facp (SHHF) rats were matched by initial tail cuff systolic blood pressure and randomly assigned to either breeding or control groups. A small group of 4 females became pseudopregnant after breeding. Initial blood pressure was mildly elevated at 141 (±2.5, SEM) mm Hg. Systolic blood pressures were recorded in all females every other day and the pressures of pseudopregnant and pregnant females were significantly greater than controls at day 6 of pregnancy, reaching a plateau by 8–10 days of pregnancy at approximately 40 mm Hg higher than nonpregnant control rats. Blood pressure began to decline in pseudopregnant females at day 12 of pregnancy, but was persistently high until after delivery in pregnant females. Half of the pregnant females were sacrificed at day 21 of gestation, and the remainder were allowed to deliver. Interestingly, despite the sustained hypertension, the mean heart weight of the hypertensive pregnant rats was 1.2 (±0.02, SEM) g, similar to normotensive females of this age and in contrast to older. Nonpregnant females of this strain with blood pressures in this range have an average heart weight of 1.6–1.8 g, suggesting that the expected cardiac hypertrophy did not develop in pregnant hypertensive females. Placental weights from sacrificed females at day 21 of gestation (0.60 ± 0.02, n = 34) were larger than those reported for spontaneously hypertensive rats (SHRs), but pup weights (2.68 ± 0.64, n = 36) were comparable. Histologic examination of the left ventricle, liver, kidney, and placenta did not reveal pathologic lesions. Thus, SHHF rats which develop pregnancy-associated hypertension had small for gestational age pups similar to SHRs but larger placental weights. The SHHF rat may be of significance as a model of spontaneous pregnancy-associated hypertension and altered rates of intrauterine growth.