Stripped rabbit distal colonic mucosa was studied in vitro in Ussing chambers to investigate the effects of adrenergic stimuli on Na+, K+, and Cl- transport. The adrenergic stimuli epinephrine and norepinephrine decrease short-circuit current in a dose-dependent manner, with a half-maximal effect at 5 x 10-7 M and a maximal effect between 10-5 and 10-4 M. The effects produced by norepinephrine and epinephrine can also be elicited by the β1-agonist dobutamine, but not by the β2-agonist terbutaline or the α-agonist phenylephrine. In addition, the effects of adrenergic stimulation can be inhibited by the β-antagonist propranolol but not by the muscarinic antagonist atropine, the α2-antagonist yohimbine, or tetrodotoxin. The decrease in short-circuit current elicited by adrenergic stimuli is accompanied by an increase in net K+ secretion with no change in net Cl- or Na+ transport. This increase in net K+ secretion elicited by β-adrenergic stimulation can be inhibited by trifluoperazine but not by indomethacin. These studies suggest that K+ transport by the colon can be regulated by adrenergic agents acting via β1-receptors.
|Journal||American Journal of Physiology - Gastrointestinal and Liver Physiology|
|Issue number||4 (13/4)|
|State||Published - 1986|