Biomaterial Database

Involvement of the motor trigeminal nucleus in respiratory phase-switching in the cat. 1997

M Pokorski, and H Gromysz

Department of Neurophysiology, Polish Academy of Sciences Medical Research Center, Warsaw, Poland.

We investigated the hypothesis that the motor trigeminal nucleus, consisting of expiratory motoneurons, might be influential in termination of inspiration. We addressed the issue by comparing the effects on neural respiration of a reversible, unilateral, pharmacologic blockade of the motor trigeminal nucleus (5M), the medial parabrachial nucleus (PB), and of other nearby structures that are neutral for respiration in anesthetized, vagotomized, paralyzed, and ventilated cats. The blockade was achieved by microinjections of 2% xylocaine, laced with Pontamine Sky Blue to identify sites of injections, from the tip of a penetrating microelectrode. Integrated phrenic neurograms were recorded to quantify the time of neural inspiration (TI), expiration (TE), and the peak phrenic amplitude. We found that blockade of the 5M caused a pattern of apneustic respiration, consisting of a selective prolongation of inspiratory phases that were interrupted by short expiratory pauses. In contrast, blockade of the PB resulted in a prolongation of both TI and TE, which corresponds to a mere slowing of respiration. The results confirmed important functions of the rostral pons in ventilatory control but pointed to the 5M rather than PB as a structure underlying the inspiratory off-switch. We conclude that the motor trigeminal nucleus may have a part in the pontine pneumotaxic mechanism.

UI	MeSH Term	Description	Entries
D008297	Male		Males
D009046	Motor Neurons	Neurons which activate MUSCLE CELLS.	Neurons, Motor,Alpha Motorneurons,Motoneurons,Motor Neurons, Alpha,Neurons, Alpha Motor,Alpha Motor Neuron,Alpha Motor Neurons,Alpha Motorneuron,Motoneuron,Motor Neuron,Motor Neuron, Alpha,Motorneuron, Alpha,Motorneurons, Alpha,Neuron, Alpha Motor,Neuron, Motor
D012119	Respiration	The act of breathing with the LUNGS, consisting of INHALATION, or the taking into the lungs of the ambient air, and of EXHALATION, or the expelling of the modified air which contains more CARBON DIOXIDE than the air taken in (Blakiston's Gould Medical Dictionary, 4th ed.). This does not include tissue respiration (	Breathing
D002415	Cats	The domestic cat, Felis catus, of the carnivore family FELIDAE, comprising over 30 different breeds. The domestic cat is descended primarily from the wild cat of Africa and extreme southwestern Asia. Though probably present in towns in Palestine as long ago as 7000 years, actual domestication occurred in Egypt about 4000 years ago. (From Walker's Mammals of the World, 6th ed, p801)	Felis catus,Felis domesticus,Domestic Cats,Felis domestica,Felis sylvestris catus,Cat,Cat, Domestic,Cats, Domestic,Domestic Cat
D005260	Female		Females
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D014278	Trigeminal Nuclei	Nuclei of the trigeminal nerve situated in the brain stem. They include the nucleus of the spinal trigeminal tract (TRIGEMINAL NUCLEUS, SPINAL), the principal sensory nucleus, the mesencephalic nucleus, and the motor nucleus.	Trigeminal Nuclear Complex,Nuclear Complex, Trigeminal,Nuclear Complices, Trigeminal,Nuclei, Trigeminal,Nucleus, Trigeminal,Trigeminal Nuclear Complices,Trigeminal Nucleus