Infant Birthweight and Postpartum Hypertension in African Green Monkeys

Abstract

Postpartum hypertension (PPHT) is characterized by significantly elevated arterial pressure developing within 48 hours following delivery. PPHT affects 2% of all pregnancies and the etiology remains unclear. We have previously reported that the African Green Monkey (AGM; Chlorocebus aethiops sabaeus) develops gestational hypertension with pathophysiological features of preeclampsia. In this study, we report characteristics of PPHT in the AGM that occurs in the absence of hypertension before or after the onset of pregnancy. Systolic blood pressures (SBP) were collected using forearm plethysmography under ketamine sedation (15 mg/kg i.m.). Animals were characterized normotensive (NT; SBP < 120 mmHg) and postpartum hypertensive (PPHT; SBP ≥ 140 mmHg developing within 48 hours following delivery). All PPHT were NT pre‐ and during pregnancy. Twenty‐four hour urine was collected in the third trimester and two weeks postpartum for three consecutive days. SBP for nonpregnant, NT was 98.7 ± 3.7 mmHg (n=18), third trimester SBP for NT was 107.0 ± 4.4 mmHg (n=5), and postpartum day 14 (PP14) SBP for NT was 94.0 ± 12.3 mmHg (n=4; p>0.05). Nonpregnant SBP for PPHT was 115.8 ± 17.6 mmHg (n=8), third trimester SBP was 112.1 ± 13.3 mmHg (n=6), and PPHT, PP14 SBP was 137.2 ± 14.3 mmHg (n=6; p <0.05 PP14 vs. third trimester). Nonpregnant plasma osmolality for NT was 306.3 ± 3.6 mOsm/kg (n=13) and third trimester NT plasma osmolality was 298.7 ± 4.6 mOsm/kg (n=7; p>0.05). Third trimester plasma osmolality for PPHT was 288.8 ± 4.6 mOsm/kg (n=6) and 312.5 ± 5.7 mOsm/kg at PP14 (n=6; p<0.05 vs. third trimester). Nonpregnant protein excretion for NT was 472.5 ± 58.0 mg/day (n=13) and 501.8 ± 104.6 mg/day in third trimester (n=5; p>0.05). In PPHT animals, nonpregnant protein excretion was 684.5 ± 152.1 mg/day (n=1), 472.7 ± 62.1 mg/day in third trimester (n=6), and 171.7 ± 68.0 mg/day at PP14 (n=5; p<0.05 PP14 vs. third trimester). Nonpregnant sodium excretion for NT was 2.4 ± 0.4 mmol/day (n=13) and third trimester for NT was 1.8 ± 0.6 mmol/day (n=5; p>0.05). Nonpregnant sodium excretion for PPHT was 0.3 ± 1.4 mmol/day (n=1), third trimester for PPHT was 2.2 ± 0.5 mmol/day (n=6), and PP14 sodium excretion for PPHT was 3.4 ± 0.6 mmol/day (n=5; p >0.05). Babies born to mothers who ultimately developed PPHT were of a higher birthweight than those born to NT mothers (NT 338.2 ± 25.5 g, n=7; PPHT 404.5 ± 14.1 g, n=6; p<0.05). This data demonstrates that postpartum hypertension in the AGM is associated with decreased protein excretion, and increased SBP after delivery when compared to the third trimester of pregnancy. The mechanisms of this PPHT are largely unknown. Ongoing studies will evaluate changes in kidney function, plasma vasopressin concentrations, and plasma renin activity. The AGM has many physiological and behavioral similarities to humans, making the species an optimal model for the study of pregnancy disorders such as PPHT.Support or Funding InformationBiomedical Science Research Group, American Heart Association Predoctoral Fellowship 17PRE33670127This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.