Study data from F.H.F. Alves et al provide new insights into bradycardia
2009 JUL 27 - (NewsRx.com) -- According to recent research from Ribeirao Preto, Brazil, "in the present study, we report the effect of insular cortex (IC) ablation caused by bilateral microinjection of the non-selective synaptic blocker CoCl2 on cardiac baroreflex response in unanesthetized rats as well as the involvement of local glutamatergic neurotransmission. Unilateral (left or right) microinjection of CoCl2 (1 nmol/100 nL) did not affect the bradycardiac response to blood pressure increase evoked by intravenous infusion of phenylephrine nor the tachycardiac response to blood pressure decrease caused by intravenous infusion of sodium nitroprusside, 10 min after CoCl2." "Bilateral microinjection of CoCl2 into IC decreased the magnitude of reflex bradycardia without affecting tachycardiac responses. Baroreflex activity returned to control values 60 min after CoCl2 microinjection, confirming its reversible effect. Further we studied the possible involvement of IC-glutamatergic neurotransmission in baroreflex modulation. We observed that bilateral microinjection of the selective NMDA receptor antagonist LY235959 (4 nmol/100 nL) into the IC decreased the magnitude of reflex bradycardia without affecting tachycardiac responses. IC treatment with the selective non-NMDA antagonist NBQX (4 nmol/100 nL) did not affect baroreflex activity," wrote F.H.F. Alves and colleagues. The researchers concluded: "The results suggest that synapses within the IC have a tonic excitatory influence on the baroreflex parasympathetic component Moreover, the present data suggest that local NMDA-receptors are involved in the IC-mediated tonic excitatory influence on baroreflex parasympathetic activity." Alves and colleagues published their study in Autonomic Neuroscience - Basic & Clinical (N-methyl-D-aspartate receptors in the insular cortex modulate baroreflex in unanesthetized rats. Autonomic Neuroscience - Basic & Clinical, 2009;147(1-2):56-63). For additional information, contact F.M.A. Correa, USP, Dept. of Pharmacology, School Medical, Bandeirantes Avenue 3900, BR-14049900 Ribeirao Preto, SP, Brazil. Publisher contact information for the journal Autonomic Neuroscience - Basic & Clinical is: Elsevier Science BV, PO Box 211, 1000 AE Amsterdam, Netherlands. Keywords: Brazil, Ribeirao Preto, Adrenergic alpha-Agonist, Antihypertensive, Blood Pressure, Bradycardia, Cardiology, Cardiotonic, Cardiovascular, Drugs, Mydriatic, Nasal Decongestant, Neuroscience, Pharmaceuticals, Phenylephrine, Sodium Nitroprusside, Sympathomimetic, Tachycardia, Therapy, Treatment, Vasoconstrictor A, Vasodilator Agent. This article was prepared by Cardiovascular Week editors from staff and other reports. Copyright 2009, Cardiovascular Week via NewsRx.com.
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