Expression of TRPM6 and TRPM7 in the preterm piglet heart

Abstract

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 TRPM6 and TRPM7 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. TRPM6 and TRPM7 mRNA expression was measured using RT-qPCR. Males had significantly lower TRPM7 expression in the left ventricle across all gestational ages compared to females. At term, both ventricles had higher TRPM7 expression at 6 h old than at birth. In preterm piglets, TRPM7 expression only increased postnatally in the right ventricle following maternal glucocorticoid exposure. At 12–24 h old, TRPM7 expression in both ventricles was lower than levels in 6 h old term Caesar piglets (113 days). Male preterm piglets may have immature myocardial Ca2+ handling and this could contribute to their poorer outcomes. Increased TRPM7 expression is the mature response to birth that is missing in preterm neonates. TRPM7 could serve as a novel target to improve cardiac function in preterm neonates.

Association between early echocardiography screening of low systemic blood flow and intraventricular hemorrhage in preterm infants: a multicenter cohort study

“…Low systemic blood ow (LSBF) is the hallmark of a transient circulatory insu ciency that may occur during the transition from fetal to neonatal physiology, especially in preterm infants. Myocardial contractility and relaxation are inherently impaired in preterm infants compared to full-term neonates [1][2][3][4] As a result, the preterm myocardium has poor tolerance to increased afterload after separation from the placenta and limited ability to deal with increased preload after the establishment of pulmonary blood ow. [5][6][7] These factors contribute to decreased cardiac output and may cause end-organ hypoperfusion and predispose preterm infants to brain ischemia and intraventricular hemorrhage (IVH).…”

Association Between Early Echocardiography Screening and Intraventricular Hemorrhage in Preterm Infants: A Prospective Observational Multicenter Study

“…Low systemic blood ow (LSBF) is de ned as a transient circulatory insu ciency during the transition from fetal to neonatal physiology. Myocardial contractility and relaxation are inherently impaired in preterm infants compared to full-term neonates [1][2][3][4] As a result, the preterm myocardium has a poor tolerance to the increased afterload after separation from the placenta and limited ability to deal with increased preload after the establishment of pulmonary blood ow. [5][6][7] These factors contribute to decreased cardiac output and may cause end-organ hypoperfusion and predispose the preterm infant to brain ischemia and IVH.…”