Role of central GABA system in hypertension induced by high salt and stress.

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We aimed to determine 1) if high salt diet augments the pressor response to shaker stress in borderline hypertensive rats (BHR) and 2) if ICV muscimol attenuates the augmented pressor response to shaker stress in high-salt BHR. The studies were done in conscious BHR and WKY of the two groups (high and normal salt diet for 5 weeks). The results demonstrated the following findings : 1) high salt intake increased resting arterial pressure and augmented pressor response to shaker stress in BHR but not in WKY, 2) ICV muscimol caused a greater decrease in mean arterial pressure and renal sympathetic nerve activity in BHR-NaCl than in BHR-control, 3) ICV muscimol attenuated the pressor response to shaker stress dose-dependently in BHR-NaCl but did not alter it in BHR-control or in WKY, and 4) Resting mean arterial pressure and the pressor response to shaker stress in BHR-NaCl after ICV muscimol did not differ form those in BHR-control. These results suggest that high salt intake may reduce the sympathetic inhibitory effect of central GABA system, which may contribute to salt-induced hypertension and the augmented response to stress in BHR.