The Role of Vagus Nerve Afferents in Hemorrhagic Hypotension, Vasovagal Syncope and Congestive Heart Failure.

The research concentrated on determining the changes in control mechanisms that occur during nonhypotensive hemorrhage--that is hemmorhage so small that there is no fall in mean arterial pressure. By this means it was possible to demonstrate that receptors in the low pressure system are responsible for antidiuretic hormone release and for the contraction of the spleen in response to changes in afferent impulses from receptors in the atria. In addition, it was shown that the probable cause why the organism in congestive heart failure has an impaired excretion of sodium and water is because changes in movements and a progressive fibrosis of the atrial walls result in a decreased operating gain in the low pressure-hypothalamic-posterior pituitary axis. Thus the work accomplished during the five years of this contract has helped to validate the hypothesis that fluid volume is regulated in the vertebrate by means of a reflex in which impulses from receptors in the heart lead to nervous and hormonal responses of the kidney. Author