title: Routes of drug delivery to the middle segment of the canine inferior vena cava in vivo.
abstract: Noradrenaline (1-3 micrograms/kg) administered into the right femoral vein caused a two-step increase in tension of the middle segment of the canine inferior vena cava, whereas noradrenaline administered into the right external jugular vein or the aortic arch caused a single-step one. The analysis of these vascular responses showed that noradrenaline administered into the femoral vein affected the inferior vena cava first from the endothelial side, distributed systemically and, then, affected the vein again from the adventitial side via the vasa vasorum. Acetylcholine (3 micrograms/kg) administered into the femoral vein caused a single-step increase in tension and could hardly reach the arterial side, while the same dose of acetylcholine administered into the aortic arch contracted the vein more largely as compared with noradrenaline. The response to noradrenaline administered topically through the vasa vasorum was augmented by administration of cocaine (2 X 10(-5) M) through the same route, while that to acetylcholine was not. These results show that acetylcholine reaches the middle segment of the inferior vena cava through the vasa vasorum in vivo more effectively than noradrenaline partly because it is not taken up by nerve terminals in the vein.
mesh_terms: D000109:Acetylcholine / Q000008:administration & dosage; D000818:Animals; D001013:Aorta, Thoracic; D001775:Blood Circulation; D002217:Carbachol / Q000008:administration & dosage; D003042:Cocaine / Q000008:administration & dosage; D004285:Dogs; D005268:Femoral Vein; D007267:Injections; D007601:Jugular Veins; D008297:Male; D009638:Norepinephrine / Q000008:administration & dosage; D014651:Vasa Vasorum; D014682:Vena Cava, Inferior / Q000187:drug effects*
chemical_list: D002217:Carbachol; D003042:Cocaine; D000109:Acetylcholine; D009638:Norepinephrine