The acute effects of elimination of the moderator reflexes upon cardiac output and total peripheral resistance in the anesthetized dog.

IN A SERIES of experiments recently completed in this laboratory, the pressoreceptor pathways were interrupted during determination of the relationships between pressure and flow in the systemic circulation. Immediately after denervation, the mean arterial pressure ascended steeply to attain a maximum value. The pressure then declined and stabilized ultimately at a hypertensive level. The total peripheral resistance determined at this plateau was consistently higher than the values observed just prior to denervation. This finding was not consonant with the studies of Charlier and Phillipot, who reported that the shaip rise in mean arterial pressure engendered by carotid occlusion" or by moderator nerve section*was accompanied by a proportionate augmentation of cardiac output. Therefore, no consistent alterations in calculated total peripheral resistance were observed in their studies. The present investigation was undertaken to establish the temporal alterations in cardiac output and total peripheral resistance after abrogation of the moderator reflexes, and to attempt to reconcile the apparent discrepancies between these studies.