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Response Properties of Baroreceptive NTS Neurons
Author(s) -
PATON JULIAN F. R.,
LI YUWEN,
SCHWABER JAMES S.
Publication year - 2001
Publication title -
annals of the new york academy of sciences
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.712
H-Index - 248
eISSN - 1749-6632
pISSN - 0077-8923
DOI - 10.1111/j.1749-6632.2001.tb03674.x
Subject(s) - baroreceptor , hyperpolarization (physics) , neuroscience , excitatory postsynaptic potential , apamin , stimulation , optogenetics , chemistry , potassium channel , inhibitory postsynaptic potential , medicine , biology , heart rate , organic chemistry , nuclear magnetic resonance spectroscopy , blood pressure
A bstract : Neurons in the nucleus of the solitary tract (NTS) responding to activation of arterial baroreceptors were recorded intracellularly using patch pipettes in an in situ arterially perfused working heart‐brain stem preparation of rat. Seven of 15 (i.e., 46%) of NTS neurons showed adaptive (nonlinear) excitatory synaptic response patterns during baroreceptor stimulation followed by an “evoked hyperpolarization.” This evoked hyperpolarization was stimulus intensity dependent and capable of shunting out a subsequent baroreceptor input. We suggest that this adaptive response behavior may be mediated, in part, by calcium‐dependent potassium currents (IK Ca ) since neurons showed spike frequency adaptation during step depolarizations and an after‐hyperpolarization after repetitive firing. Furthermore, in in vivo anesthetized rats, NTS microinjections of either charybdotoxin (225 fmol) or apamin (4.5 pmol) to block IK Ca increased the baroreceptor reflex gain. Our data purport that the responsiveness of baroreceptive NTS neurons can be regulated by intrinsic membrane conductances such as IK Ca . Modulation of such conductances during either physiological (exercise) or pathophysiological (essential hypertension) conditions may lead to changes in both the operating point and gain of the baroreceptor reflex.