Nyborg N C, Mikkelsen E O
J Cardiovasc Pharmacol. 1985 May-Jun;7(3):417-23. doi: 10.1097/00005344-198505000-00002.
We compared the responses to noradrenaline, serotonin, and potassium of isolated intramyocardial (flow-regulating) coronary and mesenteric resistance vessels of similar internal diameter (approximately 200 microns) from Wistar rats. The coronary but not the mesenteric resistance vessels had spontaneous basal tone, which was reduced by elimination of extracellular calcium, by increasing the extracellular potassium concentration up to 22 mM, and by stimulation of coronary vessels with noradrenaline. Noradrenaline always caused contraction of mesenteric resistance vessels and in coronary vessels after incubation with propranolol (3 X 10(-6) M). The noradrenaline and potassium concentration-response characteristics of the mesenteric resistance vessels were modulated by perivascular adrenergic nerve terminals, whereas no influence of nerve terminals could be shown in the coronary resistance vessels. The sensitivity of mesenteric vascular smooth muscle to noradrenaline [concentration required to give half maximal response (EC50) approximately 0.4 X 10(-6) M] and serotonin (EC50 approximately 0.3 X 10(-6) M) was higher (p less than 0.001) than the sensitivity of coronary smooth muscle (EC50 values 1.6 X 10(-6) and 1.3 X 10(-6) M, respectively). The potassium sensitivity of the coronary smooth muscle (EC50 approximately 35 mM) was higher than that of the mesenteric smooth muscle (EC50 approximately 41 mM; p less than 0.01). The respective maximal noradrenaline and serotonin responses relative to the maximal potassium response were 35 and 55% in the coronary and 127 and 120% in the mesenteric resistance vessels (p less than 0.001).
我们比较了来自Wistar大鼠的内径相似（约200微米）的离体心肌内（流量调节）冠状动脉和肠系膜阻力血管对去甲肾上腺素、5-羟色胺和钾的反应。冠状动脉阻力血管而非肠系膜阻力血管具有自发性基础张力，通过去除细胞外钙、将细胞外钾浓度提高至22 mM以及用去甲肾上腺素刺激冠状动脉，这种基础张力会降低。去甲肾上腺素总是会引起肠系膜阻力血管收缩，在用普萘洛尔（3×10⁻⁶ M）孵育后也会引起冠状动脉收缩。肠系膜阻力血管的去甲肾上腺素和钾浓度 - 反应特性受到血管周围肾上腺素能神经末梢的调节，而在冠状动脉阻力血管中未显示出神经末梢的影响。肠系膜血管平滑肌对去甲肾上腺素[产生半数最大反应所需浓度（EC50）约为0.4×10⁻⁶ M]和5-羟色胺（EC50约为0.3×10⁻⁶ M）的敏感性高于冠状动脉平滑肌（EC50值分别为1.6×10⁻⁶和1.3×10⁻⁶ M；p<0.001）。冠状动脉平滑肌对钾的敏感性（EC50约为35 mM）高于肠系膜平滑肌（EC50约为41 mM；p<0.01）。相对于最大钾反应，冠状动脉阻力血管中去甲肾上腺素和5-羟色胺的最大反应分别为35%和55%，肠系膜阻力血管中分别为127%和120%（p<0.001）。
