Dose-Response Effects of Cardiac Glycosides on Pooling and Systemic and Pulmonary Hemodynamics

摘要

The effects of ouabain and digoxin on systemic and cardiopulmonary circulations and the degree and site of vascular pooling were evaluated in this study. A major emphasis was placed on the relationship of dosage to responses observed. Experiments were performed on 32 adult mongrel dogs using a venous return preparation. Animals were divided into two groups, intact and eviscerated. Mean cumulative doses were: 27, 55, and 81 ug/kg for intact ouabain-injected dogs; 21, 42, 63, 84, and 105 ug/kg for intact digoxin-injected dogs; 26, 52, and 77 ug/kg for eviscerated ouabain-injected dogs. There was a positive correlation between amount of blood pooled and dose of cardiac glycosides given in the intact animal. The statistical difference in pooling at each dose of ouabain between intact and eviscerated animals implicated the hepatosplanchnic vascular bed as a major site of pooling. Since there was a significant statistical increase in total peripheral resistance in intact ouabain-injected dogs but not in ouabain-treated eviscerated animals, the site of peripheral resistance changes appears to be the hepatosplanchnic vascular region. Left atrial pressures rose significantly in intact and eviscerated dogs at higher ouabain doses. These findings underscore the complexity of the mechanisms of action of cardiac glycosodes and emphasize the critical importance of dosage, type of glycoside administered and individual variation of response in the canine species. (Author)