Microinjection of glycine into the nucleus ambiguus elicits tachycardia in spinal rats

V. C. Chitravanshi, S. K. Agarwal, F. R. Calaresu

Research output: Contribution to journalArticle

17 Citations (Scopus)

Abstract

In 30 male Wistar spinal (C1) rats, anaesthetized with urethane and artificially ventilated, experiments were done to study the effect on heart rate (HR) and arterial pressure (AP) of microinjection of the inhibitory amino acid glycine (Gly) into the nucleus ambiguus (NA). l-Glutamate (Glu; 1.5 nmol) was microinjected into the region of the right NA to search for sites from which decreases in AP and HR could be elicited. The decreases in HR were found to be 73.1 ± 7.0 bpm (n = 30). No changes in AP were observed. Microinjection of Gly (1 M; 2-20 nmol in 2-20 nl; n = 12) elicited a dose dependent increase in HR with no changes in AP. Microinjection of Gly 1-2 min before microinjection of Glu in 7 sites reduced significantly (P < 0.05) the decrease in HR elicited by Glu from 87.0 ± 27.3 bpm to 17.7 ± 7.2 bpm. Increase in HR elicited by Gly in the right NA of another 12 rats were not affected significantly by prior microinjection of the Gly antagonist strychine hydrochloride (30-90 pmol in 10-30 nl in one group of animals, n = 6; and 2.5 nmol in 50 nl in another group of n = 6). In addition, to determine whether the effect of Gly were cause by actions on N-methyl-d-aspartate (NMDA) receptors, kymurenic acid (KYN; 4.5 nmol in 30 nl) was microinjection into the right NA of 6 rats prior to microinjection of Gly. KYN failed to block the response to Gly microinjection and instead potentiated the HR increase elicited by Gly. These results suggest that Gly acts as an inhibitory amino acidstransmitter influencing vagal neurons in the right NA controlling HR and that the effects of Gly are mediated probably through strychnine-insensitive non-NMDA receptors.

Original languageEnglish (US)
Pages (from-to)290-294
Number of pages5
JournalBrain Research
Volume566
Issue number1-2
DOIs
StatePublished - Dec 6 1991

Fingerprint

Medulla Oblongata
Microinjections
Tachycardia
Glycine
Heart Rate
Arterial Pressure
Strychnine
Urethane
Glutamic Acid

Keywords

  • Cardiovascular regulation
  • Glycine
  • Microinjection
  • Nucleus ambigous

ASJC Scopus subject areas

  • Developmental Biology
  • Molecular Biology
  • Clinical Neurology
  • Neuroscience(all)

Cite this

Microinjection of glycine into the nucleus ambiguus elicits tachycardia in spinal rats. / Chitravanshi, V. C.; Agarwal, S. K.; Calaresu, F. R.

In: Brain Research, Vol. 566, No. 1-2, 06.12.1991, p. 290-294.

Research output: Contribution to journalArticle

Chitravanshi, V. C. ; Agarwal, S. K. ; Calaresu, F. R. / Microinjection of glycine into the nucleus ambiguus elicits tachycardia in spinal rats. In: Brain Research. 1991 ; Vol. 566, No. 1-2. pp. 290-294.
@article{789a0eec2412428f9e4e58a29d002c53,
title = "Microinjection of glycine into the nucleus ambiguus elicits tachycardia in spinal rats",
abstract = "In 30 male Wistar spinal (C1) rats, anaesthetized with urethane and artificially ventilated, experiments were done to study the effect on heart rate (HR) and arterial pressure (AP) of microinjection of the inhibitory amino acid glycine (Gly) into the nucleus ambiguus (NA). l-Glutamate (Glu; 1.5 nmol) was microinjected into the region of the right NA to search for sites from which decreases in AP and HR could be elicited. The decreases in HR were found to be 73.1 ± 7.0 bpm (n = 30). No changes in AP were observed. Microinjection of Gly (1 M; 2-20 nmol in 2-20 nl; n = 12) elicited a dose dependent increase in HR with no changes in AP. Microinjection of Gly 1-2 min before microinjection of Glu in 7 sites reduced significantly (P < 0.05) the decrease in HR elicited by Glu from 87.0 ± 27.3 bpm to 17.7 ± 7.2 bpm. Increase in HR elicited by Gly in the right NA of another 12 rats were not affected significantly by prior microinjection of the Gly antagonist strychine hydrochloride (30-90 pmol in 10-30 nl in one group of animals, n = 6; and 2.5 nmol in 50 nl in another group of n = 6). In addition, to determine whether the effect of Gly were cause by actions on N-methyl-d-aspartate (NMDA) receptors, kymurenic acid (KYN; 4.5 nmol in 30 nl) was microinjection into the right NA of 6 rats prior to microinjection of Gly. KYN failed to block the response to Gly microinjection and instead potentiated the HR increase elicited by Gly. These results suggest that Gly acts as an inhibitory amino acidstransmitter influencing vagal neurons in the right NA controlling HR and that the effects of Gly are mediated probably through strychnine-insensitive non-NMDA receptors.",
keywords = "Cardiovascular regulation, Glycine, Microinjection, Nucleus ambigous",
author = "Chitravanshi, {V. C.} and Agarwal, {S. K.} and Calaresu, {F. R.}",
year = "1991",
month = "12",
day = "6",
doi = "10.1016/0006-8993(91)91711-9",
language = "English (US)",
volume = "566",
pages = "290--294",
journal = "Brain Research",
issn = "0006-8993",
publisher = "Elsevier",
number = "1-2",

}

TY - JOUR

T1 - Microinjection of glycine into the nucleus ambiguus elicits tachycardia in spinal rats

AU - Chitravanshi, V. C.

AU - Agarwal, S. K.

AU - Calaresu, F. R.

PY - 1991/12/6

Y1 - 1991/12/6

N2 - In 30 male Wistar spinal (C1) rats, anaesthetized with urethane and artificially ventilated, experiments were done to study the effect on heart rate (HR) and arterial pressure (AP) of microinjection of the inhibitory amino acid glycine (Gly) into the nucleus ambiguus (NA). l-Glutamate (Glu; 1.5 nmol) was microinjected into the region of the right NA to search for sites from which decreases in AP and HR could be elicited. The decreases in HR were found to be 73.1 ± 7.0 bpm (n = 30). No changes in AP were observed. Microinjection of Gly (1 M; 2-20 nmol in 2-20 nl; n = 12) elicited a dose dependent increase in HR with no changes in AP. Microinjection of Gly 1-2 min before microinjection of Glu in 7 sites reduced significantly (P < 0.05) the decrease in HR elicited by Glu from 87.0 ± 27.3 bpm to 17.7 ± 7.2 bpm. Increase in HR elicited by Gly in the right NA of another 12 rats were not affected significantly by prior microinjection of the Gly antagonist strychine hydrochloride (30-90 pmol in 10-30 nl in one group of animals, n = 6; and 2.5 nmol in 50 nl in another group of n = 6). In addition, to determine whether the effect of Gly were cause by actions on N-methyl-d-aspartate (NMDA) receptors, kymurenic acid (KYN; 4.5 nmol in 30 nl) was microinjection into the right NA of 6 rats prior to microinjection of Gly. KYN failed to block the response to Gly microinjection and instead potentiated the HR increase elicited by Gly. These results suggest that Gly acts as an inhibitory amino acidstransmitter influencing vagal neurons in the right NA controlling HR and that the effects of Gly are mediated probably through strychnine-insensitive non-NMDA receptors.

AB - In 30 male Wistar spinal (C1) rats, anaesthetized with urethane and artificially ventilated, experiments were done to study the effect on heart rate (HR) and arterial pressure (AP) of microinjection of the inhibitory amino acid glycine (Gly) into the nucleus ambiguus (NA). l-Glutamate (Glu; 1.5 nmol) was microinjected into the region of the right NA to search for sites from which decreases in AP and HR could be elicited. The decreases in HR were found to be 73.1 ± 7.0 bpm (n = 30). No changes in AP were observed. Microinjection of Gly (1 M; 2-20 nmol in 2-20 nl; n = 12) elicited a dose dependent increase in HR with no changes in AP. Microinjection of Gly 1-2 min before microinjection of Glu in 7 sites reduced significantly (P < 0.05) the decrease in HR elicited by Glu from 87.0 ± 27.3 bpm to 17.7 ± 7.2 bpm. Increase in HR elicited by Gly in the right NA of another 12 rats were not affected significantly by prior microinjection of the Gly antagonist strychine hydrochloride (30-90 pmol in 10-30 nl in one group of animals, n = 6; and 2.5 nmol in 50 nl in another group of n = 6). In addition, to determine whether the effect of Gly were cause by actions on N-methyl-d-aspartate (NMDA) receptors, kymurenic acid (KYN; 4.5 nmol in 30 nl) was microinjection into the right NA of 6 rats prior to microinjection of Gly. KYN failed to block the response to Gly microinjection and instead potentiated the HR increase elicited by Gly. These results suggest that Gly acts as an inhibitory amino acidstransmitter influencing vagal neurons in the right NA controlling HR and that the effects of Gly are mediated probably through strychnine-insensitive non-NMDA receptors.

KW - Cardiovascular regulation

KW - Glycine

KW - Microinjection

KW - Nucleus ambigous

UR - http://www.scopus.com/inward/record.url?scp=0025998016&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0025998016&partnerID=8YFLogxK

U2 - 10.1016/0006-8993(91)91711-9

DO - 10.1016/0006-8993(91)91711-9

M3 - Article

C2 - 1687662

AN - SCOPUS:0025998016

VL - 566

SP - 290

EP - 294

JO - Brain Research

JF - Brain Research

SN - 0006-8993

IS - 1-2

ER -