NMDA receptors in NTS are involved in bradycardic but not in pressor response of chemoreflex

Haibara, Andréa Siqueira; Colombari, Eduardo; Chianca, D.A.; Bonagamba, Leni Gomes Heck; Machado, Benedito H.

doi:10.1152/ajpheart.1995.269.4.h1421

Cited by 66 publications

(142 citation statements)

References 17 publications

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“…It is well known that the reflex bradycardia due to peripheral chemoreflex stimulation with KCN is mediated by vagal activation (33). A similar hypothesis involving the electrophysiological effects of amiodarone could also explain the attenuation of the bradycardia induced by amiodarone in normotensive and 1K1C hypertensive rats.…”

Section: Effect Of Amiodarone On Cardiovascular Reflexesmentioning

confidence: 85%

Acute effect of amiodarone on cardiovascular reflexes of normotensive and renal hypertensive rats

Oliveira

Silva

Salgado

et al. 2005

Braz J Med Biol Res

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The aim of the present study was to evaluate the effect of amiodarone on mean arterial pressure (MAP), heart rate (HR), baroreflex, BezoldJarisch, and peripheral chemoreflex in normotensive and chronic onekidney, one-clip (1K1C) hypertensive rats (N = 9 to 11 rats in each group). Amiodarone (50 mg/kg, iv) elicited hypotension and bradycardia in normotensive (-10 ± 1 mmHg, -57 ± 6 bpm) and hypertensive rats (-37 ± 7 mmHg, -39 ± 19 bpm). The baroreflex index (∆HR/ ∆MAP) was significantly attenuated by amiodarone in both normotensive (-0.61 ± 0.12 vs -1.47 ± 0.14 bpm/mmHg for reflex bradycardia and -1.15 ± 0.19 vs -2.63 ± 0.26 bpm/mmHg for reflex tachycardia) and hypertensive rats (-0.26 ± 0.05 vs -0.72 ± 0.16 bpm/mmHg for reflex bradycardia and -0.92 ± 0.19 vs -1.51 ± 0.19 bpm/mmHg for reflex tachycardia). The slope of linear regression from ∆pulse interval/∆MAP was attenuated for both reflex bradycardia and tachycardia in normotensive rats (-0.47 ± 0.13 vs -0.94 ± 0.19 ms/mmHg and -0.80 ± 0.13 vs -1.11 ± 0.13 ms/mmHg), but only for reflex bradycardia in hypertensive rats (-0.15 ± 0.02 vs -0.23 ± 0.3 ms/mmHg). In addition, the MAP and HR responses to the Bezold-Jarisch reflex were 20-30% smaller in amiodarone-treated normotensive or hypertensive rats. The bradycardic response to peripheral chemoreflex activation with intravenous potassium cyanide was also attenuated by amiodarone in both normotensive (-30 ± 6 vs -49 ± 8 bpm) and hypertensive rats (-34 ± 13 vs -42 ± 10 bpm). On the basis of the well-known electrophysiological effects of amiodarone, the sinus node might be the responsible for the attenuation of the cardiovascular reflexes found in the present study.

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Section: Effect Of Amiodarone On Cardiovascular Reflexesmentioning

confidence: 85%

Acute effect of amiodarone on cardiovascular reflexes of normotensive and renal hypertensive rats

Oliveira

Silva

Salgado

et al. 2005

Braz J Med Biol Res

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“…In this respect, the study by Le Galloudec et al (14) documented that the hypotensive response to L-glutamate microinjected into the NTS was effectively blocked by previous microinjection of kynurenic acid. The neurotransmission of the chemoreflex (15)(16)(17)(18) and the Bezold-Jarisch reflex (19)(20)(21)(22) in the NTS also involves L-glutamate and EAA receptors. An important aspect of the neurotransmission of the different cardiovascular reflexes in the NTS is related to the subtypes of EAA receptors involved in the processing of afferent information.…”

Section: Discussionmentioning

confidence: 99%

Cardiovascular responses to microinjection of trans-(±)-ACPD into the NTS were similar in conscious and chloralose-anesthetized rats

Machado

Bonagamba

1998

Braz J Med Biol Res

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The changes in mean arterial pressure (MAP) and heart rate (HR) in response to the activation of metabotropic receptors in the nucleus tractus solitarii (NTS) with trans-(±)-1-amino-1,3-cyclopentanedicarboxylic acid (trans-(±)-ACPD) were evaluated in conscious and anesthetized Wistar, male rats weighing 240-260 g (N = 8). The responses obtained with trans-(±)-ACPD were compared with the responses to L-glutamate (1 nmol/100 nl), since in a previous study we showed that anesthesia converted a pressor response to L-glutamate microinjected into the NTS of conscious rats to a depressor response in the same rats under urethane or chloralose anesthesia. Microinjection of 3 doses of trans-(±)-ACPD (100, 500 and 1000 pmol/100 nl) produced a dosedependent fall in MAP (range, -20 to -50 mmHg) and HR (range, -30 to -170 bpm) under both conscious and chloralose anesthesia conditions. These data indicate that the cardiovascular responses to the activation of metabotropic receptors by trans-(±)-ACPD are not affected by chloralose anesthesia while the cardiovascular responses to the activation of excitatory amino acid (EAA) receptors by L-glutamate are significantly altered.

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“…PAP, MAP and HR were measured in awake freely moving rats placed inside a plastic box and the arterial catheter was connected to a pressure transducer (model CDXIII, Cobe, Lakewood, CO, USA) which was part of a Narcotrace 40 physiological recorder (Narco Bio-System, Austin, TX, USA). HR was counted with a Narco Biotachometer Coupler (model 7302) in the physiological recorder 11 . The experimental protocol consisted of intravenous injection of ABV in the experimental group (n = 12) and intravenous injection of vehicle (saline) in the control group (n = 9).…”

Section: Methodsmentioning

confidence: 99%

Cardiovascular profile after intravenous injection of Africanized bee venom in awake rats

Guimarães

Costa

Machado

et al. 2004

Rev. Inst. Med. trop. S. Paulo

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SUMMARYThe manifestations caused by Africanized bee stings depend on the sensitivity of the victim and the toxicity of the venom. Previous studies in our laboratory have demonstrated cardiac changes and acute tubular necrosis (ATN) in the kidney of rats inoculated with Africanized bee venom (ABV). The aim of the present study was to evaluate the changes in mean arterial pressure (MAP) and heart rate (HR) over a period of 24 h after intravenous injection of ABV in awake rats. A significant reduction in basal HR as well as in basal MAP occurred immediately after ABV injection in the experimental animals. HR was back to basal level 2 min after ABV injection and remained normal during the time course of the experiment, while MAP returned to basal level 10 min later and remained at this level for the next 5 h. However, MAP presented again a significant reduction by the 7 th and 8 th h and returned to the basal level by the 24 th h. The fall in MAP may contribute to the pathogenesis of ATN observed. The fall in MAP probably is due to several factors, in addition to the cardiac changes already demonstrated, it is possible that the components of the venom themselves or even substances released in the organism play some role in vascular beds.

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NMDA receptors in NTS are involved in bradycardic but not in pressor response of chemoreflex

Cited by 66 publications

References 17 publications

Acute effect of amiodarone on cardiovascular reflexes of normotensive and renal hypertensive rats

Acute effect of amiodarone on cardiovascular reflexes of normotensive and renal hypertensive rats

Cardiovascular responses to microinjection of trans-(±)-ACPD into the NTS were similar in conscious and chloralose-anesthetized rats

Cardiovascular profile after intravenous injection of Africanized bee venom in awake rats

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