Disposition of norepinephrine and epinephrine in ileum of white leghorn chicken (WLH)

Objectives: To study the disposition of (-)-norepinephrine (NE) and (-)-epinephrine (E) in ileum of WLH chicken. Method: Disposition study was conducted using oil-immersion technique of Kalsner and Nickerson. The segments of ileum were mounted in isolated organ bath using standard methods. The relaxant response of carbachol contracted ileum to NE and E alone and in presence of different combinations of inhibitors of different routes of disposition, such as at any given time only one route of disposition of CAs was left uninhibited, was recorded. Then PSS was replaced by mineral oil and recovery of relaxation was recorded. The t50 values of control experiments were compared with t50 values in presence of inhibitors. Results: The relative rate of different routes of disposition of catecholamines was in the following order: for (-)-NE, uptake 2 > COMT > uptake 1 > MAO; for (-)-E, COMT > uptake 2 > MAO = uptake 1 . The role of enzymatic degradation is almost equal to that of uptake processes for both (-)-NE and (-)-E. Conclusion: In chicken ileum reuptake is still an important route of inactivation of catecholamines but its role is almost equal to that of enzymatic degradation.