Effects of some antidepressant drugs on tryptaminergic responses of the rat jejunum.
The rat isolated jejunum was used as a functional model to screen some antidepressant drugs at the "atypical" 5-HT(7) receptor. Mianserin acted as a surmountable antagonist of 5-CT with a PA(2) value of 8.22 +/- 0.33. The apparent PK(B) of maprotiline against 5-CT was 7.67 +/- 0.24 at 100 nmol/l, but higher concentrations suppressed the maxima. An apparent PK(B) could not be obtained for amitriptyline, because 10 nmol/l reduced the E(max) of 5-CT without causing parallel displacement. Higher concentrations of 30 and 100 nmol/l caused further suppressions. Amoxapine, loxapine and desipramine (each at 100 nmol/l) caused similar effects, suppressing the E(max) values to 5-HT by approximately 50%, while lower concentrations failed to cause parallel displacements. These results further extend the activity profiles of the drugs investigated.
Liu
Haihuang
H
Department of Pharmaceutical Biology and Pharmacology, Victorian College of Pharmacy, Monash University, Parkville, Victoria 3052, Australia.
Coupar
Ian M
IM
Irving
Helen R
HR
D000818:Animals; D000928:Antidepressive Agents / Q000494:pharmacology*; D007583:Jejunum / Q000187:drug effects; D008297:Male; D009130:Muscle, Smooth / Q000187:drug effects*; D051381:Rats; D017208:Rats, Wistar; D011985:Receptors, Serotonin / Q000187:drug effects*; D012702:Serotonin Antagonists / Q000494:pharmacology*
D000928:Antidepressive Agents; D011985:Receptors, Serotonin; D012702:Serotonin Antagonists; C104425:serotonin 7 receptor