Fig. 5.

Involvement of P2 and glutamate receptors in RVLM neurons on cardiovascular changes to HDA stimulation. a Representative recording of one animal in response to stimulation of the hypothalamic defense area (HDA; 150–200 μA, 0.6 ms, 100 Hz for 5 s) before and after microinjections of suramin (10 mM) and combined blockade of suramin (10 mM) and kynurenate (50 mM) in the rostral ventrolateral medulla (RVLM). b Avereged curve of HVC responses produced by stimulation of the HDA during control, after antagonism of P2 receptors (sur) and after combined blockade of P2 and glutamate receptors (sur + kyn) in the RVLM. Black squares, averaged curve during control; dark graycircles, averaged curve after first blockade; open triangles, averaged curve after combined blockade; in light gray, standard error of the mean. c Group data showing the maximum response generated by hypothalamic stimulation after antagonism of P2 (sur RVLM), and subsequent combined blockade of P2 and glutamate receptors (sur + kyn RVLM) receptors in the ventrolateral medulla. ***P < 0.001 difference to control; n.s., nonsignificant. d Group data of increases in mean arterial pressure (MAP) and heart rate (HR) elicited by HDA stimulation before and after microinjections of suramin (10 mM), and suramin (10 mM) + kynurenate (50 mM) into the RVLM. *P < 0.05; ***P < 0.001; n.s. non-significant