Epinephrine stimulates the Na+-K+ ATPase in isolated rat jejunal crypt cells

The effect of epinephrine on the activity of the Na+-K+ ATPase was studied in isolated rat jejunal cells. The activity of the pump was assessed by mea suring the ouabain inhibitable K+ accumulation by the enterocytes using Rb- 86 as a tracer. Epinephrine stimulated significantly the Na+-K+ ATPase in c rypt cells but not in villus cells. This effect was still apparent in prese nce of propranolol and prazocin but disappeared in presence of yohimbine. A miloride did not affect the epinephrine-induced stimulation. Calcium channe l blockers and dibutyryl cAMP enhanced the activity of the pump, and exerte d respectively overlapping and additive effects with epinephrine, when adde d simultaneously. The calcium ionophore A23187 inhibited the basal activity of the ATPase and the stimulatory effect of epinephrine disappeared in its presence. These results suggest that epinephrine stimulates the Na+-K+ ATP ase in jejunal crypt cells by activating or, receptors and decreasing intra cellular calcium, and not by altering cAMP levels. (C) 2000 Elsevier Scienc e Inc. All rights reserved.