A Comparison of Synchronous Experimental Changes in Respiratory and Cardiac Rhythm of the Dog.

Abstract

This study attempts to establish the degree of similarity of response of 2 rhythmically discharging systems to similar changes in environmental conditions with the tentative assumption that similar response is indicative of a similar fundamental mechanism operating in the pace setter of respiration and the pace setter of the heart. The subject of respiratory rhythm might thus be put on a more fundamental basis and become susceptible to a more direct analysis.Lowered alveolar oxygen and intravenous injection of sodium cyanide and sodium sulphide augmented respiratory and cardiac rate in a comparable way. Comparable changes in rate were obtained after section of the vagus nerves and removal of the stellate ganglia.Administration of carbon dioxide almost invariably slowed the heart. When administered in pure oxygen, though the magnitude of respiratory movements was always increased, there was either slight or no reduction in rate or slight acceleration. When carbon dioxide was administered in a gaseous mixtu...