CARDIOVASCULAR EFFECTS PRODUCED BY ACTIVATION OF GABA

In this article by Menezes and Fontes, is looking at the role of GABA receptors A and B, in the RVLM in conscious rats.  They basically found that GABA A receptors are responsible for the depressor response that is observed and that this response is greater in conscious rats.  They used muscimol which is a GABA agonist and they microinjected bilaterally into the RVLM to activate the GABA A receptors. They also looked at GABA B receptors by using Balcofen a GABA B receptor agonist that they injected bilaterally into the RVLM. They found that this caused a pressor response however this difference was similar to the vehicle. It would have been interesting to see SNA in these rats however they did not do any nerve recordings. The article was interesting to me because they talked how anesthesia can potentiate GABA causing a greater depressor response. The problem I have with this article is that it is done in conscious animals; the animals could have been stressed prior to the injections because of the surgeries and the fact that they had cannula in their head. I would argue that MAPs could have been higher so there was a greater decrease observed in the conscious animals versus the anesthetized animals however Table 1 shows that they are similar. Also they only did the muscimol 200pmol in the anesthetized group. The final thing that I can think of is that they did not do each drug in the same animal instead they did a single drug in each animal.