Oral Presentation Neuropathophysiology - an ISH satellite 2012

Respiratory network dysfunction and hypertension in rats submitted to chronic intermittent hypoxia (#14)

Benedito H Machado 1
  1. Department of Physiology, School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, SP, Brazil
In addition to the essential role played by the neural mechanisms to provide the diaphragm and chest muscle contraction and relaxation essential for O2 and CO2 pulmonary exchanges, the respiratory neurons in the brainstem are precisely connected to the pre-sympathetic neurons in order to finely adjust the cardiac and vascular functions, accordingly with the requirements of each phase of the respiratory cycle. Recent experimental evidence point out that hypertensive states may suffer profound influence from changes in the neural respiratory network activity, which should be considered as a new important player among the several mechanisms underlying the genesis of neurogenic hypertension.  Different experimental hypertensive models dependent on increase in sympathetic outflow are associated with important changes in the pattern of coupling between respiratory and sympathetic activities. In perspective, we may take in consideration that changes in the respiratory pattern can contribute to an increased sympathetic outflow to the cardiovascular system and consequently to hypertension. To evaluate this possibility we are performing electrophysiological recordings of respiratory and pre-sympathetic neurons in the ventral medulla of rats submitted to chronic intermittent hypoxia and our findings are indicating that the major changes are related to the electrophysiological properties of respiratory neurons, which may facilitate an increase in the frequency discharge of pre-sympathetic neurons. With these data we are suggesting that changes in the respiratory network might be one of the unrevealed secrets of the hypertension in rats submitted to the chronic intermittent hypoxia.