Abstract
Using our excised canine lung lobe perfusion system with a constant pulsatile pump and an air-chamber, differences of the flow amplitude change at the inflow site of the lobe was observed on 5HT and histamine administration. After 5HT injection, the flow amplitude markedly decreased with inflow pressure elevation, on the other hand after histamine injection, there was no remarkable change regardless of the same grade pressure elevation.
To interpret these results, we represented the lobar vascular bed by two series of compliance (air-chamber)-resistance (rubber tube) circuit resembling arterial and venous side component of the lobe. With this model, only decrease of the compliance of “arterial side” exhibited the same phenomenon as 5HT, and changes of the other compliance and resistances had no effect on the flow amplitudes. These results could explain the general features of flow amplitude changes and allow for evaluation of lobar vasomotor reactivity.
Therefore we conclude that vasoconstriction occurs predominantly in arteries after 5HT injection and exclusively in veins after histamine injection, and this perfusion system is useful for detecting the sites of vasomotor reactivity on pulmonary circulation.
