Abstract
Previous study from our laboratory indicated that bilateral microinjections of CoCl2 into the IC evoked reversible decrease in the bradycardiac reflex, suggesting that synapses in the IC modulates the parasympathetic component of the baroreflex. Thus the aim of the present study was to verify the participation of the IC‐noradrenergic neurotransmission in the modulation of the parasympathetic limb of the baroreflex.Microinjection of selective noradrenergic á1‐adrenoceptor antagonist WB4101 into the IC caused a shift of the reflex threshold pressure bradycardiac responses to MAP increases toward higher MAP values (F=5, p<0.05), without affecting baroreflex gain (F=0.08, p>0.05). The effect of WB 4101 was reversible and the HR response returned to pre‐injection levels after 60 min (p>0.05). However, bilateral microinjection of the selective noradrenergic á2‐receptors antagonist RX821002 (F= 0,006, p> 0.05) did not affected baroreflex responses.Our data indicate that noradrenergic á1‐receptors in the IC are involved in the modulation of the parasympathetic baroreflex component. Financial support: FAEPA, CNPq
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