We investigated the importance of changes in intracellular Ca(2+) concentration ([Ca(2+)](i)) for amiloride-sensitive alveolar fluid clearance (AFC) in late-gestational guinea pigs. Fetal guinea pigs of 61, 68, and 69 days (term) gestation were investigated under normal conditions and after oxytocin-induced preterm labor. AFC or alveolar fluid secretion was measured using an impermeable tracer technique. At 61 days gestation there was net secretion of fluid into the lungs, and at birth the lungs cleared 49 plus minus 7% of the instilled fluid volume over 1 h. Induction of preterm labor with oxytocin induced AFC at 61 days gestation. When present, AFC was inhibited or reversed to net fluid secretion by amiloride (10(minus sign3) M). Inhibition of membrane Ca(2+) channels by verapamil (10(minus sign4) M) or depletion of intracellular Ca(2+) by thapsigargin (10(minus sign5) M) reduced AFC when net AFC was evident. Amiloride lacked an inhibitory effect on AFC when instilled with verapamil or thapsigargin. The results indicate that AFC via amiloride-sensitive pathways develops during late gestation, and that inducing preterm labor precociously may activate such pathways. Our results suggest that Ca(2+) may act as a second messenger in mediating catecholamine-stimulated AFC.
|Journal||American Journal of Physiology: Lung Cellular and Molecular Physiology|
|Publication status||Published - 2002|
Bibliographical noteThe information about affiliations in this record was updated in December 2015.
The record was previously connected to the following departments: Animal Physiology (Closed 2011) (011011000)
Subject classification (UKÄ)
- Ca(2+)-Transporting ATPase/antagonists & inhibitors/metabolism
- Calcium Channel Blockers/pharmacology
- Enzyme Inhibitors/pharmacology
- Extravascular Lung Water/*metabolism
- Gestational Age
- Guinea Pigs
- Pulmonary Alveoli/*embryology/*metabolism
- Non-U.S. Gov't