Related Experiment Video
Updated: Aug 11, 2026

In vitro Measurements of Tracheal Constriction Using Mice
Published on: June 25, 2012
Abstract:
The isolated, circular preparations of the left and right bronchi of the rat were examined for mechanical responses to neurotensin (NT) and other vasoactive peptides. NT caused concentration-dependent increases in the isometric tension of the unstimulated preparations, with an apparent affinity higher than for the cholinergic agonists but with considerably lower intrinsic activity. Pronounced tachyphylaxis to NT was observed. NT potentiated the atropine-sensitive increase in tension resulting from electrical field stimulation. Neither atropine nor methysergide abolished the response to NT in the unstimulated preparations. Bradykinin and to a lesser extent angiotensin II contracted the unstimulated preparations and both systemic peptides enhanced the cholinergic output in response to field stimulation. Substance P and VIP on the other hand were without effects in the stimulated and unstimulated bronchi. The results are consistent with the presence of receptors for NT on the presynaptic cholinergic terminals as well as on the post-synaptic smooth muscles of the rat bronchi.
Related Concept Videos
Enzyme-linked Receptors
Neurotrophin (NT) receptors are a family of RTKs, including trkA, trkB, and trkC (tropomyosin-related kinase) receptors. TrkA is specific for nerve growth factor (NGF), neurotrophin-6, and neurotrophin-7. TrkB binds...
Cholinergic Receptors: Muscarinic
The subtypes M1, M3, and M5 couple with the Gq subunit and activate the phospholipase C (PLC) activity, mobilizing intracellular Ca2+. Activation...
Cholinergic Receptors: Nicotinic
There are two types of nicotinic receptors: neuromuscular (NM/NM/N1) and neuronal (NN/NN/N2). The two families differ based on their location and selectivity to...
Adrenergic Neurons: Neurotransmission
Synthesis: Catecholamine synthesis requires tyrosine, which is taken...

