Table 4.
Baroreflex response before and after GABA receptor blockade in the RVLM
| Control | RVLM GABA Receptor Blockade | |||||
|---|---|---|---|---|---|---|
| Δ MAP (mm Hg) | Δ RSNA (% C) | Δ RSNA/Δ MAP | Δ MAP (mm Hg) | Δ RSNA (% C) | Δ RSNA/Δ MAP | |
| Protocol 1 (n=7) | 37.5 ± 5 | −61 ± 8.1 | −1.8 ± 0.25 | 34 ± 4.1 | −1.3 ± 1.2* | −0.04 ± 0.04* |
| Protocol 2 (n=8) | 40 ± 4.3 | −55 ± 10.5 | −1.4± 0.2 | 30 ± 2.2 | −5 ± 2.4* | −0.15 ± .08 * |
In right NTS lesioned rats, phenylephrine (PE, 5 μg/kg, i.v.) increased MAP similarly before and after left RVLM Bicuculline (BIC) (Protocol 1) or BIC+CGP35348 (Protocol 2). Decreases in RSNA were reduced by left RVLM GABA receptor blockade. Estimated baroreflex gain (Δ RSNA/Δ MAP) was decreased by 98% with RVLM GABAA receptor block and by 89% with GABAA + GABAB receptor blockade. Values = mean ± SEM;
P ≤ 0.05 compared to corresponding control value.