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2251296 
Journal Article 
Mechanism of Decreased Venous Return with Nitroglycerin 
Cyong J-C; Tanaka, K; Horiguchi, Y; Tsuchiya, R; Itoh, H 
1976 
Yes 
Japanese Journal of Pharmacology
ISSN: 0021-5198
EISSN: 1347-3506 
NIOSH/00133439 
26 
1 
123-125 
The effect of nitroglycerin (55630) (NG) on the systemic and pulmonary vascular bed was examined in dogs. The mode of action of NG under controlled cardiac output with a mechanical left ventricle was studied in mongrel-dogs. The left ventricle was replaced by a sigma motor pump which maintained constant cardiac output of 60 to 70 milliliters per kilogram (ml/kg) per minute. Fifty micrograms per kilogram NG was injected intraaortically through a cannula inserted in the descending aorta. Systemic arterial pressure, femoral venous pressure, left auricular outflow, superior vena cava flow, and inferior vena cava flow were compared to baseline measurements. Venous return to the left heart from lesser circulation, direct venous return from the upper half of the body, and direct venous return from the lower half body were measured. The total of the latter two parameters was considered as the total venous return to the right heart from systemic circulation. Following NG administration, mean left auricular outflow decreased 60ml during the first minute, then gradually increased over 2 minutes to become stable at a flow slightly above control. Total venous return to the right heart showed only an insignificant increase and was significantly different from left auricular outflow during the first 2 minutes. NG caused significant decrease in mean femoral arterial pressure, but only a slight and insignificant increase in superior and inferior venae cavae flow. Femoral venous pressure remained fairly constant during NG administration. The authors conclude that decrease in left auricular outflow has beneficial effects in anginal attack due to the reduction in left ventricular loading. The decrease induced by pulmonary vasodilatation may be the primary mode of action of NG in the relief of angina pectoris.