The Finkleman Preparation

Isolated segments of rabbit jejunum show spontaneous rhythmic contractions which can be affected by both stimulation of sympathetic nerves and administration of pharmacological agents which mimic the actions of sympathetic neurotransmitters. Increasing the concentration of norepinephrine in the organ bath relaxes the intestine, within 1-2 minutes, to a state where it is more relaxed than when it is set up in the organ bath. Once the concentration of norepinephrine in the organ bath reaches a level where there is sufficient to activate available adrenoceptors a further increase has no additional effect on the level of relaxation. Guanethidine and imipramine reduce norepinephrine uptake potentiating its effects.

Both propranolol (beta-adrenoceptor blocker) and phentolamine (alpha-adrenoceptor blocker) partially block the effects of norepinephrine added to the organ bath suggesting that the effects of released norepinephrine on intestinal smooth muscle cells are mediated by both alpha- and beta-adrenoceptors.

	True	False
Isolated segments of rabbit jejunum show regular rhythmic activity in the absence of nerve stimulation
Norepinephrine causes a dose-dependent relaxation of the rabbit jejunum
The effects are slow in onset beginning at least 10 minutes after epinephrine is added to the organ bath
Propranolol, a beta-adrenergic receptor blocking drug, potentiates the effects of norepinephrine added to the organ bath
Phentolamine, an alpha-adrenergic receptor agonist, partially inhibits the relaxation caused by addition of norepinephrine to the organ bath
Guanethidine has no effect/slightly reduces the effect of exogenously administered norepinephrine
Imipramine potentiates the effects of exogenously administered norepinephrine

The Finkleman Preparation DEMO