[Role of area postrema of medulla in regulation of rat cardiovascular activity].

OBJECTIVE

To explore the role of area postrema (AP) of medulla in control of cardiovascular functions in rat.

METHODS

(1) Sprague Dawley rats were anaesthetized with urethane and pentobarbital and the AP was stimulated by electrical stimulus with intensity of 0.1 mA and frequencies ranged 10 approximate, equals 80 Hz. (2) Excitatory amino acid L-glutamate (L- Glu, 0.1 approximate, equals 0.5 mol/L) was microinjected into AP in urethane anaesthetized rats and the changes of mean arterial pressure (MAP) and heart rate (HR) were recorded.

RESULT

(1) When the frequencies of 10 Hz, 20 Hz and 40 Hz were used, the electrical stimulation of AP caused decrease of MAP and HR (P<0.001),while the electrical stimulation with the frequencies of 60 Hz and 80 Hz caused an increase of MAP (P<0.05) but a decrease of HR (P<0.001). (2) Microinjection of L-Glu at 0.1 mol/L had no effect on MAP and HR (P>0.05), but it decreased MAP and HR at 0.15 mol/L (P<0.001, P<0.05). The MAP was increased (P<0.001) but HR (P<0.05) was decreased at the concentrations of 0.2 mol/L and 0.5 mol/L, respectively.

CONCLUSION

Alterations of MAP and HR induced by electrical or chemical stimulation on AP of medulla are related to the frequency of electrical stimulation or concentration of L-Glu.