Serotonin-induced chloride secretion in hen colon. Possible second messengers.
1. Serotonin, 100 microM, induces a peak increase in short circuit current of about 150 microA/cm2 and in cord conductance of about 7 mS/cm2 and a more prolonged increase of 30 microA/cm2 and 1.4 mS/cm2 which lasts more than 30 min in hen colon. 2. The peak increase in short circuit current and cord conductance is due to a concomitant Cl- secretion. 3. The second messenger, which mediates Cl- secretion, increases in short circuit current and cord conductance, is cyclic AMP as theophylline, 0.5 mM, increases the response in short circuit current to 1 microM serotonin from 38 +/- 5 to 78 +/- 8 microA/cm2 and in g from 1.1 +/- 0.4 to 2.0 +/- 0.3 mS/cm2. 4. Theophylline, 0.5 mM, also sensitizes the hen colon to cyclic AMP yielding an EC50 of 0.24 +/- 0.03 mM in the presence of theophylline compared with an EC50 of 2.3 +/- 0.2 mM in the absence of theophylline. 5. Manipulations of other putative second messenger systems, such as the prostaglandins/leucotrienes, the phosphoinositides and external Ca2+ or calmodulin-sensitive enzymes, did not influence the serotonin response in short circuit current and cord conductance, thus ruling out their importance as intracellular mediators.
Hansen
M B
MB
Department of General Physiology and Biophysics, Panum Institute, University of Copenhagen, Denmark.
Bindslev
N
N
D000818:Animals; D001095:Arachidonic Acids / Q000502:physiology; D002118:Calcium / Q000502:physiology; D002147:Calmodulin / Q000502:physiology; D002645:Chickens / Q000378:metabolism*; D002712:Chlorides / Q000378:metabolism*; D003106:Colon / Q000378:metabolism; D000242:Cyclic AMP / Q000502:physiology; D004594:Electrophysiology; D005260:Female; D007413:Intestinal Mucosa / Q000378:metabolism*; D010716:Phosphatidylinositols / Q000502:physiology; D011493:Protein Kinase C / Q000502:physiology; D015290:Second Messenger Systems / Q000502:physiology*; D012701:Serotonin / Q000502:physiology*
D001095:Arachidonic Acids; D002147:Calmodulin; D002712:Chlorides; D010716:Phosphatidylinositols; D012701:Serotonin; D000242:Cyclic AMP; D011493:Protein Kinase C; D002118:Calcium