Effect of dexamethasone on cardiovascular response induced by norepinephrine in nucleus tractus solitarii.
OBJECTIVE
To study the effect of dexamethasone on cardiovascular response induced by norepinephrine (NE) in nucleus tractus solitarii (NTS).


METHODS
The variations of cardiovascular action caused by these drugs were observed after injection of mifepristone (Mif), dexamethasone (Dex), bicuculline (Bic), and NE into the medial and intermediate NTS.


RESULTS
Microinjection of Dex (0.39 mmol.L-1, 0.1 microL) into the medial and intermediate NTS abolished the vasodepressed response to NE (8 mmol.L-1, 0.1 microL) microinjected into the same area 10 min later, and the inhibition did not disappear until 4 h. The rapid inhibitory effects of Dex on NE vasodepression was not antagonized by Mif (4.66 mumol.L-1, 0.1 microL), but it was blocked by Bic (3.24 mumol.L-1, 0.1 microL).


CONCLUSIONS
Dex abolished cardiovascular response to NE microinjected into NTS which may be mediated by GABAA receptor.
Ou-Yang
M
M
Department of Physiology, Norman Bethune University of Medical Sciences, Changchun, China.
Ge
G H
GH
Wang
S
S
D000818:Animals; D001640:Bicuculline / Q000494:pharmacology; D001794:Blood Pressure / Q000187:drug effects*; D003907:Dexamethasone / Q000494:pharmacology*; D005938:Glucocorticoids / Q000494:pharmacology*; D006339:Heart Rate / Q000187:drug effects; D008845:Microinjections; D015735:Mifepristone / Q000494:pharmacology; D009638:Norepinephrine / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D011965:Receptors, Glucocorticoid / Q000037:antagonists & inhibitors; D017552:Solitary Nucleus / Q000187:drug effects / Q000502:physiology*
D005938:Glucocorticoids; D011965:Receptors, Glucocorticoid; D015735:Mifepristone; D003907:Dexamethasone; D009638:Norepinephrine; D001640:Bicuculline