Neonatal asphyxia. An approach to physiology and management

Metabolic acidosis in the newborn period

In this chapter we have described the metabolic diseases which are known to have caused acidosis during the newborn period. We have also provided some diagnostic and treatment guidelines. The occurrence of acidosis in a newborn baby should initiate several actions, aimed simultaneously at treatment and diagnosis. An initial blood gas determination, accompanied by the results of serum electrolytes and glucose, will, in most instances, separate respiratory from metabolic causes. Finding of an increased anion gap and/or presence of hypoglycaemia should direct attention towards errors in intermediary metabolism.

Ontogenesis of beta-adrenergic receptors in the ovine placenta

Radioligands with high specific activity and high affinity have recently become available to study the beta-adrenergic receptor (BAR). BAR may be important in the placenta for mediating a variety of metabolic and hemodynamic effects of catecholamines including placental hormone synthesis and secretion, placental glycogenolysis, and placental blood flow. Little is known regarding the development of the BAR. We have used the tritiated radioligand dihydroalprenolol to study the ontogenesis of BAR in the fetal and maternal portions of the ovine placenta. The receptor number decreased from 415 fmoles . mg-1 of protein at 120 days' gestation to 226 fmoles . mg-1 at 145 days; this trend was highly significant (r = -0.822, p less than 0.01). Similar changes were noted in the dissociation constant. Downward regulation as a result of fetal neurosympathetic maturation is proposed as an explanation for this observation.