Glutamate transporter type 3 knockout leads to decreased heart rate possibly via parasympathetic mechanism.
Parasympathetic tone is a dominant neural regulator for basal heart rate. Glutamate transporters (EAAT) via their glutamate uptake functions regulate glutamate neurotransmission in the central nervous system. We showed that EAAT type 3 (EAAT3) knockout mice had a slower heart rate than wild-type mice when they were anesthetized. We design this study to determine whether non-anesthetized EAAT3 knockout mice have a slower heart rate and, if so, what may be the mechanism for this effect. Young adult EAAT3 knockout mice had slower heart rates than those of their littermate wild-type mice no matter whether they were awake or anesthetized. This difference was abolished by atropine, a parasympatholytic drug. Carbamylcholine chloride, a parasympathomimetic drug, equally effectively reduced the heart rates of wild-type and EAAT3 knockout mice. Positive immunostaining for EAAT3 was found in the area of nuclei deriving fibers for vagus nerve. There was no positive staining for the EAATs in the sinoatrial node. These results suggest that EAAT3 knockout mice have a slower heart rate at rest. This effect may be caused by an increased parasympathetic tone possibly due to increased glutamate neurotransmission in the central nervous system. These findings indicate that regulation of heart rate, a vital sign, is one of the EAAT biological functions.
Department of Anesthesiology, University of Virginia Health System, 1 Hospital Drive, PO Box 800710, Charlottesville, VA, 22908-0710, USA.
Jiao
J
Deng
Jiejie
J
Li
Liaoliao
L
Li
Chenzhuo
C
Feng
Lize
L
Xiong
Zhiyi
Z
Zuo
D000818:Animals; D001285:Atropine / Q000008:administration & dosage; D002490:Central Nervous System / Q000378:metabolism; D050580:Excitatory Amino Acid Transporter 3 / Q000235:genetics* / Q000502:physiology; D018698:Glutamic Acid / Q000235:genetics / Q000378:metabolism*; D006339:Heart Rate / Q000235:genetics*; D006801:Humans; D051379:Mice; D018345:Mice, Knockout; D012849:Sinoatrial Node / Q000187:drug effects; D009435:Synaptic Transmission; D014630:Vagus Nerve / Q000187:drug effects
D050580:Excitatory Amino Acid Transporter 3; C493399:Slc1a1 protein, mouse; D018698:Glutamic Acid; D001285:Atropine