Role of Catecholamines in the Control of Newborn Kidney Adenine Nucleotide Content

Abstract

During the 1 st h of extrauterine life, the adenine nucleotide content of the rat kidney is modified: the ATP level increases (+30%) while ADP and AMP are lowered (––30 and ––50%, respectively). This leads to a high value of energy charge in the newborn kidney (0.89 vs. 0.80 in the fetus). It was possible to obtain in utero a similar modification of ATP, ADP, AMP concentrations by injections to the fetuses of cAMP, dibutyryl cAMP, or isoprenaline. Conversely, the postnatal changes in adenine nucleotide content could be prevented by administration to the fetus, just before birth, of β- or β₁-adrenoreceptor antagonists. Therefore the rise of kidney energy charge following parturition appears to be under hormonal control. Glucagon had no effect on kidney adenine nucleotide content. It is strongly suggested that the catecholamines released at the time of parturition are the triggering factor of this evolution.

Effects of birth on energy metabolism in the rat kidney

“…Birth clearly induced a quick increase in phosphocreatine content, which reached 6.1 + 1.1 ,umol/g of protein in the newborn (1 hpostpartum) kidney. As previously reported [5,6], kidney ATP content increased by 38 % during the same period. There was a slight decrease in creatine content between the fetal and 1 h-post-partum stages (from 59.2 to 50.5 ,umol/mg of protein; P = 0.05).…”

“…In previous studies [5,6], we have shown that birth induces a stimulation of ATP production in the rat kidney: within the first hour of extra-uterine life, the whole-organ ATP content, ATP/ADP ratio and energy charge (ATP + 0.5ADP)/(ATP + ADP + AMP) values increase significantly. Using adrenoreceptor agonists and antagonists, we have demonstrated [6] the role of catecholamines as a triggering factor of these modifications. In the present work, we studied the nature of metabolic pathways involved in this neonatal increase of kidney ATP production.…”

“…Fetuses were delivered by caesarian section, after cervical dislocation of the mother, in the morning of day 21 post coitum. The 1 h-post-partum newborns were obtained as described in [6]; 6 hand -day-post-partum newborns were spontaneously delivered animals; they were killed by cervical dislocation. Developmental stages were monitored by Table 1.…”

“…Homogenates were prepared from two kidneys of the same animal as 4 (w/v) suspension in ice-cold 6.8 Mglycerol/60 mM-Na2HPO4/NaH2PO4, pH 7.4, with a motor-driven Teflon/glass homogenizer. HC104 tissue extracts were made as described in [6]. Fumarase (EC 4.2.1.2) and ,J-hydroxyacyl-CoA dehydrogenase (EC 1.1.1.35) activities were assayed fluorimetrically at 20-22°C by the Burch et al [12] method.…”