MSNA and Trigeminal Nerve Stimulation

Ever wonder how the impressive diving reflex seen in seals might be related to human physiology? In this engaging podcast, Guest Editor Nisha Charkoudian (U.S. Army Research Institute of Environmental Medicine) interviews lead author James P. Fisher (University of Birmingham, United Kingdom) and Zeljko Dujic (University of Split School of Medicine, Croatia) about a fascinating new study by Fisher and colleagues designed to investigate whether the sympathetic effects of the trigeminal nerve reflex have additive effects with the reflexes due to exercise. The authors used ice packs applied the face to stimulate the trigeminal nerve, and added handgrip exercise to evaluate whether excessive sympathoexcitation could result. What was the response of muscle sympathetic nerve activity when hand-grip exercise was added to the facial cooling-stimulation of the diving reflex? What implications does this study have for elite breath-hold divers, for recreational divers, or for patient populations who want to participate in water sports? Listen and find out.

James P. Fisher, Igor A. Fernandes, Thales C. Barbosa, Eliza Prodel, John H. Coote, Antonio Claudio L. Nóbrega, Lauro C. Vianna Diving and exercise: The interaction of trigeminal receptors and muscle metaboreceptors on muscle sympathetic nerve activity in humans Am J Physiol Heart Circ Physiol, published March 1, 2105, DOI: 10.1152/ajpheart.00728.2014.