冠循環の神経体液性調節に関する研究 : 自律神経作働性物質の冠循環に及ぼす作用

抄録

The nervous control of the coronary circulation has been widely investigated, but many problems still remain unsolved. It is generally accepted that the coronary vessels are dilated by the sympathetic nerve and constricted by the vagal nerve. However, recent work of our clinic stands against these former concept. In this paper, for further study of the nervous control of the coronary vessels from pharmacological standpoint, the effects of some autonomic drugs on the coronary circulation were investigated.Young dogs with open-chest and artificial respiration, ranging in weight from 10 to 15 kg, were used under sodium thiopental (Ravonal) anesthesia. The left coronary artery was perfused from the animal's own right femoral artery and the coronary inflow was measured with rotameter. Then one ml. of drug solution, which contained 1×10^-9-10^-4 gm epinephrine, 1×10^-3-10^-4 gm norepinephrine, 1×10^-9-10^-5 gm acetylcholine, or 1×10^-7-10^-4 g ATP^-Na, were injected into the tubing leading to the coronary artery from the rotameter using 10 seconds, and the changes of coronary blood flow were calcutated.Results were as follows : 1) Doses above 1×10^-3-10^-7 gm of epinephrine increased coronary flow. In these cases, the coronary flow was increased slowly after the injection and duration of the increase in coronary blood flow was comparatively long. It often lasted several minutes. The increase in coronary blood flow was almost always associated with the elevation of blood pressure and change of heat rate. When large doses of epinephrine was injected, initial decrease in coronary blood flow was followed by a marked increase.2) The effect of norepinephrine was essentially the same as that of epinephrine in quality. Doses above 1×10^-7-10^-6 gm of norepinephrine increased coronary blood flow, heart rate and blood pressure. Long sustained increase in coronary blood flow was observed. When large doses were injected, initial decrease was also observed.3) Injection of small doses of acetylcholine or ATP-Na often increased the coronary blood flow without remarkable changes of blood pressure or heart rate. Large doses of acetylcholine (1×10^-6gm or more) decreased heart rate, blood pressure and coronary blood flow. The effects of acethylcholine and ATP-Na on coronary blood flow appeared more rapidly than those of epinephrine, but lasted for 15-30 seconds.4) As mentioned above, acetylcholine and ATP-Na increased coronary blood flow without remarkable changes of heart rate and blood pressure, but in no experiment epinephrine or norepinephrine augmented the coronary blood flow without any evinence of irritation of myocardium, such as elevation of blood pressure, increase in heart rate and vigor of myocardial contraction. Therefore it can be concluded that in this experiment the direct coronary vasodilatative effects of acetylcholine and ATP-Na were demonstrated, but such effects of epinephrine and norepinephrine were not observed. From present data the presence of the direct action of epinephrine and norepinephrine cannot be decided. But in seems that the direct action of these drugs are vasoconstrictive to coronary artery. At least it appears that the coronary vasodilatative effects of these drugs chiefly result from the hemodynamic and metabolic changes induced by their effects on the myocardium.