Electrolyte transport responses to secretagogues in neonatal versus adult rabbit jejunum.

The ability of the neonatal and adult rabbit jejunum to respond to different exogenous stimuli of electrolyte transport was investigated in vitro. When mounted in Ussing chambers, jejunum from neonatal rabbits exhibited a higher basal short circuit current and lower potential difference compared to jejunum from adult rabbits. As a result, basal conductance was approximately 50% higher in the neonatal group. When the tissue was subjected to electrical field stimulation, neonatal jejunum was significantly less responsive to stimulation with respect to change in short circuit current, particularly at submaximal stimulus strength and stimulus duration. The neonatal jejunum was less responsive than adult jejunum to exogenous application of prostaglandin E2 and 5-hydroxytryptamine, and more responsive to histamine. There was no significant difference in the responses to carbachol, epinephrine, leukotriene D4 or platelet-activating factor. The neonatal rabbit jejunum exhibited a greater capacity to synthesize prostaglandin E2 and the peptidoleukotrienes, and had a higher tissue content of 5-hydroxytryptamine than the adult rabbit jejunum.