The goal of this research is to gain a better understanding of the mechanisms which coordinate the activation of the upper airway muscles with that of the diaphragm during postnatal development. Dysfunction in this system results in episodes of obstructive apneas found in premature infants and adults with obstructive sleep apnea. These experiments are designed to measure the changes in the membrane properties of the respiratory motoneurons controlling the diaphragm and upper airways. The specific aim of this proposal is to determine the role the intrinsic properties of these motoneurons play in shaping their respiratory discharge behavior during development. More specifically, do intrinsic properties of the motoneuron control its neuronal behavior? The evolution of cellular and ionic mechanisms controlling this behavior will be studied during postnatal development. From these studies, we hope to ascertain if there is any difference in the process of maturation between these two motor pools and if so, what is the relative sequence of attaining their adult discharge characteristics? The active and passive membrane properties of these respiratory motoneurons will be investigated using intracellular recording and labeling techniques. The ionic mechanisms underlying these properties will be delineated using single electrode current and voltage clamp in both in vivo and in vitro mammalian preparations. An in vitro spinal cord and brainstem since will be developed in order to study the alteration in specific ionic currents during development.