Maternal Allopurinol Prevents Cardiac Dysfunction in Adult Male Offspring Programmed by Chronic Hypoxia During Pregnancy

Abstract

Integrating functional and molecular levels, we investigated the effects of maternal treatment with a xanthine oxidase inhibitor on the programming of cardiac dysfunction in adult offspring using an established rat model of hypoxic pregnancy. Female Wistar rats were divided into normoxic or hypoxic (13% O₂) pregnancy±maternal allopurinol treatment (30 mg kg^-1 d^-1). At 4 months, hearts were isolated from 1 male per litter per outcome variable to determine cardiac function and responses to ischemia-reperfusion in a Langendorff preparation. Sympathetic dominance, perfusate CK (creatine kinase) and LDH (lactate dehydrogenase) and the cardiac protein expression of the β₁-adrenergic receptor, the M₂ Ach receptor (muscarinic type-2 acetylcholine receptor), and the SERCA2a (sarcoplasmic reticulum Ca²⁺ ATPase 2a) were determined. Relative to controls, offspring from hypoxic pregnancy showed elevated left ventricular end diastolic pressure (+34.7%), enhanced contractility (dP/dt_max, +41.6%), reduced coronary flow rate (-21%) and an impaired recovery to ischemia-reperfusion (left ventricular diastolic pressure, area under the curve recovery -19.1%; all P<0.05). Increased sympathetic reactivity (heart rate, +755.5%; left ventricular diastolic pressure, +418.9%) contributed to the enhanced myocardial contractility ( P<0.05). Perfusate CK (+431%) and LDH (+251.3%) and the cardiac expression of SERCA2a (+71.4%) were also elevated ( P<0.05), further linking molecular markers of cardiac stress and injury to dysfunction. Maternal allopurinol restored all functional and molecular indices of cardiac pathology. The data support a link between xanthine oxidase-derived oxidative stress in hypoxic pregnancy and cardiac dysfunction in the adult offspring, providing a target for early intervention in the developmental programming of heart disease.

Keywords: allopurinol; developmental programming; hypoxia; oxidative stress; pregnancy; rats.

Figure 1.

Cardiac basal function. Values are dot plots, as well as mean±SEM. Groups are normoxic (N; n=9), hypoxic (H; n=8), hypoxic treated with allopurinol (HA; n=8), and normoxic treated with allopurinol (NA; n=9) pregnancy. Significant differences (P<0.05) are *vs N; †vs H (2-way ANOVA+Tukey test). CFR indicates coronary flow rate; dP/dt _max and dP/dt _min, the maximum and minimum first derivatives of the left ventricular pressure; HW, heart weight; LVDP, left ventricular developed pressure; and LVEDP, left ventricular end diastolic pressure.

Figure 2.

Cardiac sympathetic dominance. Values are dot plots, as well as mean±SEM for the ratio of cardiac chronotropic and inotropic responses to isoprenaline and carbachol. Groups are normoxic (N; n=9), hypoxic (H; n=8), hypoxic treated with allopurinol (HA; n=8), and normoxic treated with allopurinol (NA; n=9) pregnancy. Significant differences (P<0.05) are *vs N; †vs H (2-way ANOVA+Tukey test). HR indicates heart rate; and LVDP, left ventricular developed pressure.

Figure 3.

Cardiac ischemia-reperfusion challenge. Values are dot plots or mean±SEM for the cardiac left ventricular developed pressure (LVDP) response to ischemia-reperfusion and the perfusate CK (creatine kinase) and LDH (lactate dehydrogenase) levels. Groups are normoxic (N; n=9), hypoxic (H; n=8), hypoxic treated with allopurinol (HA; n=8), and normoxic treated with allopurinol (NA; n=9) pregnancy. Significant differences (P<0.05) are *vs N; †vs H (2-way ANOVA+Tukey test).

Figure 4.

Cardiac proteins expression. Values are dot plots, as well as mean±SEM. Groups are normoxic (N; n=6), hypoxic (H; n=6), hypoxic treated with allopurinol (HA; n=6), and normoxic treated with allopurinol (NA; n=6) pregnancy. Significant differences (P<0.05) are *vs N; †vs H (2-way ANOVA+Tukey test). SERCA2A indicates sarcoplasmic reticulum Ca²⁺ ATPase 2a.

Figure 5.

Summary of key findings. Hypoxic pregnancy programmes cardiac dysfunction in adult male offspring. Mechanisms involved include an increase in xanthine oxidase, cardiac sympathetic dominance, and altered cardiac calcium biology. Maternal treatment with the xanthine oxidase inhibitor, allopurinol, prevents the programmed cardiac dysfunction in adult male offspring, normalizing the cardiac sympathetic dominance and altered cardiac calcium biology. Therefore, oxidative stress derived from xanthine oxidase plays an important role in the programming of cardiac dysfunction by developmental hypoxia. Maternal treatment with allopurinol should be considered as clinical intervention against the programming of heart disease in adult offspring of human high-risk pregnancy. IR indicates ischemia-reperfusion; LV, left ventricle; ROS, reactive oxygen species; and SERCA2a, sarcoplasmic reticulum Ca2+ ATPase 2a.