Effects of epinephrine on resistive and compliant properties of the canine vasculature

The peripheral circulation of 22 anesthetized dogs was separated into 3 parallel regions, where the outflow from each region could be measured and both outflow and inflow pressures could be controlled. The authors were thus able to estimate arterial and venous resistance and venous compliance for each region. The pressure dependency of these parameters was determined before and during continuous infusion of epinephrine (3 μg/kg/min). Epinephrine increased the arterial resistance in all regions but did so in such manner as to increase the fraction of cardiac output perfusing the splanchnic region. The venous resistances were all elevated by epinephrine and showed a greater pressure dependency than during control. Systemic venous compliance was found to be pressure dependent during both control and epinephrine administration, decreasing by nearly 50% from the lowest to the highest venous pressures (4 to 12 mmHg) investigated. Splanchnic compliance was found to comprise nearly half the total systemic compliance. Results were interpreted using an extension of the parallel compartment model of the peripheral circulation described by Caldini, Permutt, Waddell, and Riley.