Expression of and in the preterm piglet heart.

Preterm infants are at increased risk of death and disability, and cardiovascular instability after birth is a contributing factor. Immaturity of calcium handling in the preterm heart may limit myocardial contractility and cardiac output. Two transmembrane cation channels, TRPM6 and TRPM7, may regulate intracellular cardiac calcium in the neonatal period. The aim of this study was to determine and mRNA expression in piglet hearts in late gestation, and the effects of sex, maternal glucocorticoids, and the transition to extrauterine life. Left and right ventricular tissue was collected at a range of gestational ages from cesarean delivered piglets at birth and at 6 h old. Additional groups included piglets exposed to maternal glucocorticoid treatment and spontaneously born term piglets at 12-24 h old. and mRNA expression was measured using RT-qPCR. Males had significantly lower expression in the left ventricle across all gestational ages compared to females. At term, both ventricles had higher expression at 6 h old than at birth. In preterm piglets, expression only increased postnatally in the right ventricle following maternal glucocorticoid exposure. At 12-24 h old, expression in both ventricles was lower than levels in 6 h old term Caesar piglets (113 days). Male preterm piglets may have immature myocardial Ca handling and this could contribute to their poorer outcomes. Increased expression is the mature response to birth that is missing in preterm neonates. could serve as a novel target to improve cardiac function in preterm neonates.