Non-uniform effects of neurohumoral agents on the internal diameter in parallel and series arranged small arteries in rabbit hindlimb.

Abstract

Using X-ray angiography, the internal diameter (ID) of 31 sites of arteries in the hindlimb, i.e., the iliac, main femoral, profundal femoral, circumflex femoral, saphenous, and popliteal arteries, was measured in anesthetized rabbits. ID under the control condition was 294-1,796 micrometers, but was changed to 376-1,828 micrometers, 127-1,914 micrometers, and 423-2,098 micrometers with administration of hexamethonium bromide, noradrenaline, and phentolamine, respectively. The constrictor effects of noradrenaline and plasma catecholamine were larger in the femoral artery than in the iliac artery. At the transition site from the iliac to the femoral artery, ID per unit length increased from 190 micrometers/10 mm in the control to 320 micrometers/10 mm with noradrenaline. The constrictor effects of sympathetic nerve activity (SNA) on the profundal femoral, circumflex femoral, saphenous, and popliteal arteries varied among 19 out of 20 sites. Plasma catecholamine constricted ID at 18 sites but dilated it at 2 sites. Noradrenaline constricted ID at all 20 sites, particularly in the popliteal and saphenous arteries. It was concluded that the effects of SNA and plasma catecholamine on ID on rabbit hindlimb arteries were qualitatively and quantitatively non-uniform among different arteries and at different sites of the given artery.