Synaptic activation of hypoglossal respiratory motorneurons during inspiration in rats.
Recent work has suggested glutamatergic and cholinergic synapses, and electric coupling may be involved in the activation of hypoglossal motorneurons during inspiration, however their relative importance is unknown. In this study we examined the excitatory inputs to hypoglossal motorneurons in a brainstem slice preparation. Focal application of D-2-amino-5-phosphonovalerate significantly inhibited a long lasting inward current evoked during inspiration. 6-Cyano-7-nitroquinoxaline-2,3-dione completely blocked the post-synaptic currents that increased in frequency and amplitude during inspiration and also reduced the long lasting inward current. Nicotinic receptors and gap junctional communication, blocked by D-tubocurare and carbenoxolone, respectively, contributed significant but smaller inputs to hypoglossal motorneurons during inspiration. In summary, non-N-methyl-D-aspartate (NMDA) receptors constitute the largest excitatory drive to hypoglossal neurons during inspiration, while NMDA, nicotinic receptors and gap junctions are also actively involved.
Wang
Jijiang
J
Department of Pharmacology, George Washington University, 2300 Eye St NW, Washington, DC 20037, USA.
Irnaten
Mustapha
M
Venkatesan
Priya
P
Evans
Cory
C
Baxi
Sunit
S
Mendelowitz
David
D
D015763:2-Amino-5-phosphonovalerate / Q000494:pharmacology; D018750:6-Cyano-7-nitroquinoxaline-2,3-dione / Q000494:pharmacology; D000818:Animals; D002229:Carbenoxolone / Q000494:pharmacology; D003472:Curare / Q000494:pharmacology; D005071:Evoked Potentials / Q000187:drug effects / Q000502:physiology; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D017629:Gap Junctions / Q000502:physiology; D007002:Hypoglossal Nerve / Q000166:cytology / Q000502:physiology*; D009046:Motor Neurons / Q000502:physiology*; D018733:Nicotinic Antagonists / Q000494:pharmacology; D051381:Rats; D017470:Receptors, Glutamate / Q000187:drug effects / Q000502:physiology; D016194:Receptors, N-Methyl-D-Aspartate / Q000037:antagonists & inhibitors; D011978:Receptors, Nicotinic / Q000187:drug effects / Q000502:physiology; D017661:Receptors, Presynaptic / Q000187:drug effects / Q000502:physiology; D015656:Respiratory Mechanics / Q000502:physiology*; D013569:Synapses / Q000502:physiology*
D018691:Excitatory Amino Acid Antagonists; D018733:Nicotinic Antagonists; D017470:Receptors, Glutamate; D016194:Receptors, N-Methyl-D-Aspartate; D011978:Receptors, Nicotinic; D017661:Receptors, Presynaptic; D018750:6-Cyano-7-nitroquinoxaline-2,3-dione; D015763:2-Amino-5-phosphonovalerate; D003472:Curare; D002229:Carbenoxolone