Mischel, NA and Mueller, PJ. Am J Physiol Regul Integr Comp Physiol (resubmitted)
I wanted to be the first to post a blog on a hot new paper that is destined to be accepted in AJP: Reg in the next couple of weeks. It's the first first author paper from a student in an up and coming laboratory examining neuroplasticity in cardiovascular regulation that occurs following sedentary versus physically active conditions. In the study the author observed increased resting and stimulated sympathetic nerve activity. Neuroplasticity in the brainstem is a possible mechanism since one of the methods used to increase sympathetic nerve activity was with direct microinjections of the excitatory amino acid, glutamate. Interestingly, the authors also observed enhanced sympathoexcitation with unloading of arterial baroreceptors with the vasodilator nitroprusside. Although baroreceptor unloading is typically associated with withdrawel of GABAergic inhibition of the RVLM (i.e. disinhibition), there are a few studies that have implicated glutamate in the the baroreflex (see Maryov and Head, 2003). Lastly, the authors test vascular sensitivity by injections of the alpha one agonist phenylephrine. In a classic move, they test the responses in the presence of ganglionic blockade to remove any compensatory actions of the baroreflex from influencing their results. All an all an interesting paper that is likely to be cited by several since it implicates the splanchnic circulation as a target for physical (in)activty dependent neuroplasticity. As in their review from 2010, they make use of a "physical (in)activity" nomenclature to promote the idea that these changes could be the result of remaining sedentary, being physically active or both. They suggest future studies are warrant to distinguish between these possibilities.
-Posted by Pat (upon resubmission of Nick's 1st paper, of course!
No comments:
Post a Comment