Swimming exercise changes hemodynamic responses evoked by blockade of excitatory amino receptors in the rostral ventrolateral medulla in spontaneously hypertensive rats.

Biomed Res Int. 2014;2014:487129. doi: 10.1155/2014/487129. Epub 2014 Feb 18. Ogihara CA, Schoorlemmer GH, Lazari Mde F, Giannocco G, Lopes OU, Colombari E, Sato MA. In this paper, they looked at differences in glutamate-mediated RVLM activity between sedentary and swim-exercise-trained rats. Previous work from the group showed that using GABA to inhibit the NTS results in enhanced hindlimb vasodilation in exercise-trained SHR rats. This time, they wanted to look at things further down the autonomic regulation line, so they used SHR rats again (exercised and sedentary) and gave microinjections of kynurenic acid into the RVLM. They found the same enhanced conductance/vasodilation in swimmers compared to seds as before, and that these results seen in SHR rats were not seen in WKY rats. To look at how that vasodilation was regulated peripherally, they blocked nitricic oxide production via L-NAME inhibition of nitric oxide synthase. They saw that the RVLM-glutamate-receptor-blockade-induced-vasodilation was attenuated in exercised rats but not in sedentary rats. Again, these results were not seen in WKY rats, suggesting that SHR rats' disorder is rooted in the RVLM as well as in peripheral effects. Just like we talked about in our lab meeting today, we tend to look at the RVLM as the end of the story, but there are a lot of other things involved that we have to keep in mind. -DH