Heterogeneous behavior of the canine arterial and venous wall. Importance of the endothelium.

TLDR

The study aimed to assess how endothelial cells influence the differing responses of arterial and venous walls. Canine arterial and venous rings, with and without endothelium, were tested for isometric tension in Krebs‑Ringer bicarbonate solution. Endothelial cells produced strong inhibitory responses to acetylcholine, ATP, thrombin, and arachidonic acid in arteries but only transient inhibition in veins; removal of endothelium reduced norepinephrine‑anoxia augmentation in both vessels, while in veins arachidonic acid and thrombin induced endothelium‑dependent tension increases, and overall endothelial effects were inhibitory in arteries and excitatory in veins.

Abstract

Experiments were designed to determine the contribution of endothelial cells to the heterogeneous behavior of the arterial and venous wall. Rings of canine femoral, pulmonary, saphenous, and splenic arteries and veins, with and without endothelium, were mounted for isometric tension recording in Krebs-Ringer bicarbonate solution. Endothelium-dependent inhibitory responses to acetylcholine, adenosine triphosphate, bovine thrombin, and arachidonic acid were prominent in the arteries. In the veins, only transient endothelium-dependent relaxations to these substances were observed. Removal of the endothelium decreased the augmentation of the response to norepinephrine caused by anoxia in both arteries and veins. In the veins, arachidonic acid and thrombin caused endothelium-dependent increases in tension during contractions evoked by norepinephrine. The endothelium-independent inhibitory effects of isoproterenol and adenosine and the excitatory effects of acetylcholine and ATP were more pronounced in the veins than in the arteries. These experiments demonstrate that in the arterial and venous wall the endothelial cells can contribute to both inhibitory and excitatory responses of the smooth muscle cells of the media. Inhibitory endothelial responses prevail in the arteries, and excitatory ones in the veins.